Australopithecus couple
The earliest known hominins were for a long time were thought to come from the genus “Australopithecus” , which first appeared between 3 million and 4 million years ago. But now, after discoveries made in the 1990s and early 2000s, many scientists think the oldest hominins belong to another genus, “Ardipithecus”, that first appeared at least 4 million years ago and may be as old as six million years old. Some even older creatures that have been discovered may be hominins. A genus is a class of animals or plants that usually consist of more than one species.

There are many out there that still believe Australopithecus is the oldest hominin. They don’t regard Ardipithecus as a hominin. There are also some who don’t regard Australopithecus as a hominin either. Australopithecus means "southern ape" a reference to the fact that the first Australopithecus fossils were found in southern Africa. [Sources: Australopithecus, Rick Gore, National Geographic, February 1997; Australopithecus, Donald Johanson, National Geographic, March 1996]

Australopithecus mostly lived between two million and four million years. Some have said the genus may be as old as 7.5 million years. In February 1984 an Australopithecine jawbone with two molars — dated at 4 million years ago by nearby fossils and 5.4-5.6 million years ago by rocks — was found near Lake Baringo, Kenya.

The genus Australopithecus is considered the likely precursor of the genus Homo, to which modern humans belong. Though its cranium is comparable to a chimpanzee's, Australopithecus walked upright, as humans do. This was a surprise to anthropologists when the first Australopithecines were discovered because it had been assumed that big-brain of Homo was preceded by a big-brain ancestor, and having a big brain and walking upright evolved together. [Source: Wikipedia]

Australopithecus afarensis

Scientists have different theories about which hominins evolved into more developed species and which hominins lead to evolutionary dead ends. Some scientists believed that the “Homo” genus evolved from “Australopithecus afarensis” . Others believe it developed from “Australopithecus afarensis” . “Australopithecus Bosei” and “Australopithecus robustus” are believed to be evolutionary dead ends because they lived at the same time as “Homo” species. The various theories are difficult to prove.

Categories with related articles in this website:
Early Hominins and Human Ancestors (23 articles); Neanderthals, Denisovans, Hobbits, Stone Age Animals and Paleontology (25 articles); Modern Humans 400,000-20,000 Years Ago (35 articles); First Villages, Early Agriculture and Bronze, Copper and Late Stone Age Humans (33 articles)

Websites and Resources on Hominins and Human Origins: Smithsonian Human Origins Program ; Institute of Human Origins ; Becoming Human University of Arizona site ; Talk Origins Index ; Last updated 2006. Hall of Human Origins American Museum of Natural History ; Wikipedia article on Human Evolution Wikipedia ; Human Evolution Images; Hominin Species ; Paleoanthropology Links ; Britannica Human Evolution ; Human Evolution ; National Geographic Map of Human Migrations ; Humin Origins Washington State University ; University of California Museum of Anthropology; BBC The evolution of man"; "Bones, Stones and Genes: The Origin of Modern Humans" (Video lecture series). Howard Hughes Medical Institute.; Human Evolution Timeline ; Walking with Cavemen (BBC) ; PBS Evolution: Humans; PBS: Human Evolution Library; Human Evolution: you try it, from PBS; John Hawks' Anthropology Weblog ; New Scientist: Human Evolution; Fossil Sites and Organizations: The Paleoanthropology Society; Institute of Human Origins (Don Johanson's organization); The Leakey Foundation; The Stone Age Institute; The Bradshaw Foundation ; Turkana Basin Institute; Koobi Fora Research Project; Maropeng Cradle of Humankind, South Africa ; Blombus Cave Project; Journals: Journal of Human Evolution; American Journal of Physical Anthropology; Evolutionary Anthropology; Comptes Rendus Palevol ; PaleoAnthropology

Australopithecus Body Features, Size and Sex

Australopithecines (plural of Australopithecus) were short and stocky with apelike features such as long arms, thick waistlines and chimpanzee-like faces. They had short and stocky apelike bodies, and brains closer in size to a chimpanzee than a modern human. Males were about 1.37 meters tall and females 1.14 meters.

Judging from the well developed eye sockets and short nasal clefts of skulls, Australopithecines probably had keen eyesight but a poor sense of smell. It is believed they avoided danger by looking above the grasses for potential predators such as hyenas, lions and leopards.

Australopithecines appeared to sexually dimorphic, meaning that males were significantly larger than females, a trait shared by gorillas and orangutans. It is difficult to determine their age and lifespan because the rate in which they matured is not known.

In a study published in December 2007 in the journal Science, a team led Charles Lockwood of University College London theorized that dominant male “Australopithecus robustus” may have had large harems like modern gorillas do today. Based on the study of 35 fossilized A. robustus” remains, researchers found that adult males were considerably larger than adult females, a relationship usually associated with a dominate male and harem relationship in other animals. As it true with dominant males in other animal species male “A. robustus” kept on growing even after reaching adulthood while females stopped growing when they reached breeding age.

Australopithecus discovery sites


At least eight species of Australopithecus (collectively known as Australopithecines) have been identified. It is not clear how they were related. Some are called robust australopithecines (australopiths) because they had heavy features and large jaws with powerful muscles for smashing and grinding tough food. The other species had heavy jaws but were more slightly built.

Lucy — of the species Australopithecus afarensis (which lived about 3.9 million to 2.9 million years ago at several sites in Ethiopia and Kenya) — and the Taung Child — of the species Australopithecus africanus (lived about 3.3 million to 2.1 million years ago in southern Africa) — are the most famous Australopithecus fossils. Catharine Paddock wrote in Medical News Today: “For a long time, it was thought that humans descended in a straight line from one pre-human species living 3 million to 4 million years ago. This theory was backed up by the fossil record - including the discovery of Lucy - until the end of the 20th century. [Source: Catharine Paddock PhD, Medical News Today, May 28, 2015]

“But then, the new century brought some surprises - researchers discovered Kenyanthropus platyops in Kenya and Australopithecus bahrelghazali in Chad. Both these species date from Lucy's period - challenging the idea that humans descended from a single hominin species. At first, scientists were highly sceptical following the discoveries in Kenya and Chad. But some started to change their view when in 2012, Dr. Haile-Selassie announced the discovery of the 3.4 million-year-old Burtele partial foot fossil, confirming the likelihood of multiple hominin species living at the same time 3 million to 4 million years ago.”

Different Australopithecines

1) Australopithecus africanus
a) A. africanus (lived about 3.3 million to 2.1 million years ago in southern Africa)
b) A. deyiremeda (lived about 3.5 -3.3 million years ago in northern Ethiopia)
c) A. garhi (lived about 2.5 million years ago in Ethiopia)
d) A. sediba (lived about 2 million years ago in southern Africa)

2) Also called Paranthropus (lived about 2.6 million to 1.1 million years ago)
a) P. aethiopicus (lived about 2.5 million years ago in southern Ethiopia)
b) P. robustus (lived about 2 million to 1.2 million years ago in southern Africa)
c) P. boisei (lived about 2.4 million to 1.4 million years ago in Olduvai Gorge in Tanzania)

3) Also called Praeanthropus
a) A. afarensis (lived about 3.9 million to 2.9 million years ago at several sites in Ethiopia and Kenya)
b) A. anamensis (lived about 4.2 million to 3.9 million years ago at several sites in Ethiopia and Kenya)
c) A. bahrelghazali (lived about 3.6 million years ago in Chad)


Complexity of the Hominid Scene 3 Million Years Ago

Pete Spotts wrote in Christian Science Monitor: “New fossils from Ethiopia are providing fresh evidence that some 3 million to 4 million years ago, ancestors to modern humans may have been more diverse than previously thought. That diversity would have led to an inadvertent test to see which species was best able to weather changes in climate and habitat during that period, some researchers suggest. So far, that would appear to be Australopithecus afarensis, represented by its most famous example, Lucy, discovered in 1974 by Donald Johanson and Tom Gray. [Source: Pete Spotts, Christian Science Monitor, May 27, 2015]

“But Lucy and her species were not the only Australopithecine on the block. Over the years, researchers have reported uncovering two additional species from this period. If this latest discovery holds up, it would bring to four the number of known Australopithecus species living within this million-year span. These species range from Ethiopia to Chad. The research team that found the new fossils – upper and lower jaws that included teeth – have classified the find as belonging to a new species of hominin, a subset of hominids that includes modern humans and our direct ancestors. The researchers suggest that the new species, which they have dubbed Australopithecus deyiremeda, was a close relative to A. afarensis. The team's analysis appeared the journal Nature.

“A. deyiremeda's remains were found at a site in Ethiopia's Afar region known as Woranso-Mille, about 22 miles north of another site rich in A. afarensis fossils – pointing to the possibility that the two species roamed the same general region at about the same time. With several Australopithecus species living in eastern and central Africa in the same general period, "we're looking at hominins who are potential candidates as human ancestors," says Henry Bunn, a paleoanthropologist at the University of Wisconsin at Madison. During this period, known as the middle Pliocene, the climate was getting cooler and drier. Vegetation and food resources were changing.

“Looking at these Australopithecines, "you could almost think of them as ecological experiments as populations try to exploit new habitats and new resources successfully," says Dr. Bunn, who was not a member of the research team. "Most of those species went extinct."

In the past, researchers had broken the last 5 million years of hominin evolution into blocks of 1 million to 2 million years, he explains. Based on the fossil evidence available at the time, "you only had one species per block of time," he says. At about 2 million years ago, with the emergence of the genus Homo, hominins became more diverse.

With Lucy and subsequent discoveries, it now appears that the middle Pliocene also hosted a diverse array of hominins that included at least one additional group beyond Australopithecines – a group represented by Kenyanthropus platyops. The newly discovered jawbones and teeth – dated to between 3.5 and 3.3 million years ago – shared some characteristics with A. afarensis and others with K. platyops. This period also coincides with the appearance of the earliest stone tools yet found, a discovery announced last week in another paper in Nature.

“The new species is yet another confirmation that Lucy’s species, Australopithecus afarensis, was not the only potential human ancestor species," according to Yohannes Haile-Selassie, curator of physical anthropology at The Cleveland Museum of Natural History who headed the team making the discovery. “Current fossil evidence from the Woranso-Mille study area clearly shows that there were at least two, if not three, early human species living at the same time and in close geographic proximity,” he said in a prepared statement.

Laetoli Footprints

Laetoli footprints
A series of 3.6 million-year-old footprints left in volcanic ash by an early hominin were discovered in Laetoli, Tanzania. The 69 prints were made by two adults that appear to have walked side by side. The two sets of prints parallel each other, about a foot apart. The Laetoli footprints were likely made by Australopithecus afarensis individuals. They made headlines in the 1970s as the earliest clear evidence of upright walking by our ancestors.

One set seems to be made by a large male, and the other by a smaller female. Inside the larger prints are prints from a third individual, possible a child. At one point the prints are so close together the hominins could have been holding hands. At another place the small one seems to be walking behind the large one. At another point the smaller one halted in mid stride, perhaps to turned around and look at something.

The Laetoli prints were found with prints from an ancient horse, rhinoceros and antelope. Most anthropologists believe the hominin prints were made by an Australopithecus species but they are not sure whether they were made by afarensis species like Lucy, another known species, or a mystery species whose fossilized bones have not yet been discovered.

The hominins that made the prints had a humanlike stride, wrote paleoanthropologist Donald Johanson in National Geographic: "a strong stride with the heel, followed by a push-off with the big toe to propel the body forward. Their big toes do not splay out from the rest of the foot like the divergent big toes all other primates have."

Zach Zorich wrote in Archaeology magazine: “The 3.6-million-year-old footprints at Laetoli, Tanzania, have fascinated archaeologists since they were discovered in 1976. These prints preserve, in volcanic ash, that most characteristic of behaviors—the act of walking—among early humans. Understanding how early humans moved is important because efficient, upright locomotion was one of the first evolutionary traits that set them apart from other ape species. [Source: Zach Zorich, Archaeology Volume 64 Number 6, November/December 2011]

Significance and Discovery of Laetoli Footprints

20120202-Laetoli footprint.png
Laetoli footprints
The Laetoli prints provides the best evidence that early hominin walked like modern humans — body upright, legs striding side by side. Unlike the feet of chimpanzee, which have a splayed toe that separates from the foot like a thumb, the Laetoli tracks are made by feet with all the toes parallel to the axis of the foot (the same as humans).

The large gap between the large toe and the rest of the toe meant the Laetoli creature no longer spent much time climbing trees. There was also no evidence of knuckle walking of any kind. Little Foot, a 3- to 3.5- million-year-old fossil foot from a “ Australopithecus africanus” foot found in South Africa, has an ape-like splayed toe and humanlike ankle which shows that feet ideal of bipedalism evolved slowly.

The Laetoli footprints were discovered in Tanzania by a worker on Mary Leakey's team after falling down trying to dodge a piece of elephant dung flung at him by one of his friends. The footprints were found in rock created by ash created by an eruption from the nearby Sadiman volcano.Accurate dating was made possible by measuring the radioactive decay of particles found in the ash.

A year after the site was discovered, it was covered in river sand filled with seeds of acacia trees that sprouted and almost destroyed the tracks with their roots. In 1993, an emergency operation was launched to kill the trees and excavate the tracks. To preserve the tracks for future generations a granular fill and geo-textile of synthetic material was placed on top of prints at Laetoli to preserve them. The geo-textile kept the granular fill in place while allowing air to circulate and killing off damaging roots with a herbicide that was developed to prevent weeds from growing on foot paths in real east developments.

Short Legs, Running and Aggression

20120202-Laetoli_recreated 2.JPG
Laetoli footprints recreation
The short legs of the Australopithecus were long thought to be needed to climb trees. In a paper published in the journal Evolution in March 2007, David Carrier of the University of Utah argued that short legs more likely evolved to make males better fighters by giving them a lower center of gravity and better balance. Their superior fighting ability in turn made them attractive to females and the trait was passed on.

“Australopiths maintained short legs for two million years because a squat physique and stance helped the males fight over access to females,” Carrier told the Times of London. “With short legs your center of mass is closer to the ground. It’s going to make you more stable so that you can’t be knocked doff your feet as easily. And with short legs you have great leverage as you grapple your opponent.”

Carrier analyzed the heights and limb lengths of modern great apes and compared this data with with levels of aggression. He found that for each primate, apart from modern man, the female had relatively longer legs than males and this suggested a link between leg length and aggression. Modern man is the exception to this rule in that it has long legs and is highly aggressive. Carrier said they “traded advantages of being able to stand their ground for the ability to run away or walk distances.”

Ancient human species such as the australopithecines were unable to run very fast for long periods because they lacked Achilles tendons. With the exception of gibbons all close human relatives — namely chimpanzees, gorillas orangutans — lack Achilles tendons and likely early human ancestors lacked them too. Bill Sellars of the University of Manchester told the Times of London. “Without Achilles tendons you are rubbish at running. You can’t go very fast and you use an awful lot of food to get from A to B. Humans and, strangely, gibbons have great big Achilles tendons...Pursuit running pretty much relies on running...If Lucy has no Achilles tendon she’d be far to inefficient to have been any kind of pursuer. It wouldn’t have stopped her from scavenging, but she wouldn’t have been much of a hunter.” Running is thought to have developed about 2 million years ago. It is a pogo-stick-like motion using tendons in the legs as elastic springs.

3-D Laser Scans Show Laetoli Footprints Were Made Surprisingly Modern Feet

In 2011, a team led by Robin Crompton of the University of Liverpool published a study of the Laetoli footprints using 3-D laser scans that appeared to show that Australopithecus afarensis had anatomically modern feet, approximately 2 million years before they were thought to have evolved. [Source: Zach Zorich, Archaeology Volume 64 Number 6, November/December 2011 ^^]

Zach Zorich wrote in Archaeology magazine: “Crompton's study analyzed 11 of the Laetoli footprints likely to have been made by the same individual, and combined the scanned results to come up with a single composite footprint. The method revealed a detailed picture of how forces were transmitted between the foot and the ground. The composite print was compared to modern ones made by apes and humans walking over a plate that measures downward force. The Laetoli print showed evidence of an arch in the midfoot and a forward-pointing big toe that pushed off with each step, traits similar to those of modern human feet. ^^

New Laetoli Footprints

Australopithecus afarensis footprinte

Thirteen 3.66 million-year-old footprints were found in 2015 about 150 meters away from the famed Laetoli footprints of a similar age found by the Leakeys in the 1970s, The footprints are impressions left in volcanic ash that later hardened into rock. Their comparatively large size, averaging a bit over 26 centimetres, suggest they were made by a male member of the species known as Australopithecus afarensis. [Source: Associated Press, December 14, 2016]

Ian Sample wrote in The Guardian“The markings reveal that the ancient human relatives walked side by side for at least 30 metres. The footprints were laid down in a layer of ash that was subsequently buried, but which when moistened retained the tracks like clay. A first analysis of the footprints suggests that they were made when a male, three females and a child passed through what is now Laetoli in the African country. The individuals almost certainly belong to a species of hairy bipedal ape called Australopithecus afarensis which is known to have lived in the region. The most famous member of the species, known as Lucy, lived in the Hadar area of Ethiopia 3.2 million years ago. A mere 1.1 metre tall, she was tiny in comparison to those who left their marks in Tanzania. The male stood more than half a metre taller, at 165 centimeters (5ft 5in), making him the largest Australopithecus yet recorded. His impressive stature – for his species – led researchers to nickname him Chewie after the towering hairy Wookiee in Star Wars.[Source: Ian Sample, The Guardian, December 14, 2016 |=|]

“Researchers unearthed the tracks by accident when they began to excavate test pits that had been called for as part of an assessment of the impact of building a proposed museum on the site in Tanzania. Marco Cherin, a palaeontologist at the University of Perugia in Italy, helped to excavate the tracks after the first prints were discovered by a team in Tanzania. “When we reached the footprint layer and started to clean it with a soft brush and saw the footprints for the first time, it was really one of the most exciting times of my life,” he said. |=|

“The layer of ash that preserved the tracks has been dated to 3.66 million years old, the same age as a similar sequence of hominin, or human ancestor, footprints found nearby by famed palaeontologist Mary Leakey in the 1970s. Researchers now want to return to the site to dig a trench that links the excavation pits and then work outwards, in the hope of revealing more tracks. “We are pretty sure that at least one more individual is waiting for us, and possibly more. Our goal is to discover new individuals,” Cherin said. |=|

New Laetoli Footprints Made by Five Individuals, Including a Big Male

Initial analysis of new Laetoli footprints suggests that they were made by a male, three females and a child. Ian Sample wrote in The Guardian: “Having uncovered the footprints and measured them, the scientists used a number of mathematical models to calculate the heights of the different individuals. If the scientists are right that the group consisted of a tall male with three adult females and a child, it would bolster the theory that Australopithecus afarensis was polygynous, meaning that, like gorillas, males would have had several female partners at once. The adult females stood about 140 centimeters tall. [Source: Ian Sample, The Guardian, December 14, 2016 |=|]

“Measurements of the length and width of the footprints, the angle of the gait and the stride lengths allowed the scientists to calculate rough weights for the five. The tall male came in at the heaviest, weighing 48.1kg, with the lightest only 28.5kg. “These footprints enrich our knowledge about the most ancient hominin footprints in the world,” Cherin told the Guardian. “But they tell us something about the makers too, in this case that we think there were significant differences between the males and females. This is the most striking thing. A tentative conclusion is that the group consisted of one male, two or three females, and one or two juveniles, which leads us to believe that the male – and therefore other males in the species – had more than one female mate,” Cherin added. Details of the tracks are published in the journal, eLife. |=|

“Giorgio Manzi, director of the archaeological project in Tanzania, said the evidence portrayed several human ancestors moving through the landscape after a volcanic eruption that was followed by rain. “The footprints of one of the new individuals are astonishingly larger than anyone else’s in the group, suggesting that he was a large male member of the species. In fact, the 165 centimeter stature indicated by his footprints makes him the largest Australopithecus specimen identified to date.” In being so short, it seems that Lucy was an outlier.

“William Jungers of Stony Brook University in New York said: “To judge by the profound scientific impact of the first set of Laetoli footprints, we can expect the new ones to figure prominently in future narratives of the origins of humans. They will likely stimulate new research and debate for years to come.” |=|

Laetoli footprints

New Laetoli Footprints: a Big Male and a Harem?

Associated Press reported: “He stood a majestic five-foot-five, weighed around 100 pounds and maybe had a harem. That's what scientists figure from the footprints he left behind some 3.7 million year ago. He's evidently the tallest known member of the pre-human species best known for the fossil skeleton nicknamed "Lucy," reaching a stature no other member of our family tree matched for another 1.5 million years, the researchers say. Researchers named the new creature S1, for the first discovery made at the "S" site. From the footprints, they calculated that he stood about roughly five-foot-five and weighed around about 100 pounds. [Source: Associated Press, December 14, 2016 ^]

“They figured that he loomed at least more than 20 centimetres above the individuals who made the other tracks, and stood maybe 7 centimetres taller than a large A. afarensis specimen previously found in Ethiopia. "Lucy," also from Ethiopia, was much shorter at about 3½ feet. The findings are described in a report released Wednesday by the journal eLife. Authors include Giorgio Manzi of Sapienza University in Rome, Marco Cherin of the University of Perugia in Italy, and others. ^

“Nobody knows the ages or sexes of any of the track-makers, although the size of the latest footprints suggest they were made by a male. It's quite possible that the new discovery means A. afarensis males were a lot bigger than females, with more of a difference than what is seen in modern humans, the researchers say. That's not a new idea, but it's still under debate. The large male-female disparity suggests A. afarensis may have had a gorilla-like social arrangement of one dominant male with a group of females and their offspring, the researchers said. ^

“But not everybody agrees with their analysis of S1's height. Their estimate is suspect, says anthropologist William Jungers, a research associate at the Association Vahatra in Madagascar who wrote a commentary on the study. That's because scientists haven't recovered enough of an A. afarensis foot to reliably calculate height from footprints, he said. Philip Reno, an assistant anthropology professor at Penn State who didn't participate in the new work, said he believed the height estimate was in the right ballpark. But he's not convinced that S1 was really taller than the large Ethiopian A. afarensis. So rather than setting a record, "I think it confirms about the size we thought the big specimens were," Reno said. Manzi and Cherin said they can't be sure S1 was taller than the Ethiopian specimen. "We only suggest," they wrote in an email.” ^

bones with tool marks from Dikika Ethiopia

Cut Marks on 3.4-Million-Year-Old Bone: Earliest Evidence of Tools?

In 2009, 3.4-million-year-old bones — found in Dikika, Ethiopia, near site where a Lucy-like hominin was discovered — with slashes, parallel marks and other cut marks that appear to have been made with stone tools, was presented as evidence that stone tools were produced more than 800,000 years than earlier thought and they could have been made by a possible human ancestor such as Lucy (Australopithecus afarenis).

The marks were made on a rib from a cow-like hoofed creature and a thigh bone from a goat-size animal, possibly from an impala, gazelle or antelope. It was argued that someone used stones to trim flesh from bone and perhaps crush bones to get at the marrow inside. It was also argued that this was the earliest evidence of meat and marrow consumption by hominins. No tools were found at that site, so it was unclear whether the marks were made with handmade tools or just naturally sharp rocks. [Source: Charles Q. Choi, Live Science, May 20, 2015]

"We were just walking along when we discovered the two bones," Shannon McPherron, an archaeologist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, told The Guardian. "We picked up the rib fragment, flipped it over and there were these two, clear marks. Soon after, we found the second bone, also with a lot of marks on it. Right away we knew we had something potentially important." [Source: Ian Sample, The Guardian, August 11, 2010]

cut marks made by a stone tool in the Dikika bones of a cow-size animal

Jennifer Viegas wrote in Discovery News: “Various types of electron microscopy, along with chemical analysis, determined that cut marks were inflicted while one or more individuals carved meat off the bones with a sharp stone tool. Percussion marks were also created when a stone tool broke open the bones to extract their nutritious marrow. The fossilized bones were found sandwiched between volcanic deposits, which permitted reliable dating of them. Before this discovery, the world’s oldest human evidence for butchery dated to 2.5 million years ago and came from Bouri and Gona, Ethiopia. No human remains were found in association with those fossilized prey bones, but A. afarensis remains were previously unearthed near the recent Afar Region discoveries. [Source: Jennifer Viegas Discovery News, August 11, 2010]

Unlike 2.5-million-year-old stone flakes found Ethiopia in 1997, which were mostly sharp cutting edges or the remains of the tool-making process, the stone tools that made the marks in Dikika were likely used as they were found. Detailed analysis of the cut marks on the bones seemed to indicate they were significantly different from tooth and claw marks made by predators. One of the marks was embedded with a small fragment of stone, according to a report in the journal, Nature.

Tia Ghose wrote in Live Science: “The bones were found several years ago in the history-rich sediments of Dikika, an area in the Awash River valley in Ethiopia,” an arid region that “has yielded some of the best examples of both early hominin fossils and fossils from anatomically modern early humans. Though archaeologists have not found hominin fossils at this particular site, just a few hundred meters away, other research teams previously found the nearly intact skeleton of a 3.3-million-year-old baby girl Australopithecus, dubbed "the Dikika baby" or "Lucy's baby." (The Dikika baby is not truly Lucy's baby, since she lived 100,000 years before Lucy.) [Source: Tia Ghose, Live Science, August 20, 2015]

“At this particular spot, other paleoanthropologists sifting through 3.4-million-year-old sediments found two bones — one from an antelope-size creature and another from a buffalo-size animal — that had a total of 12 distinctive marks. In a 2010 study published in the journal Nature, researchers proposed that someone used a cutting tool to make those marks. But the news was considered shocking: In 2010, the earliest known stone tools, from Gona, Ethiopia, dated to 2.6 million years ago. In 2011, another research group weighed in, writing in a paper in the journal Proceedings of the National Academy of Sciences that the marks on the bones were likely not cut marks, but instead the marks of sediments rubbing over the bones as wild beasts trampled them over the millennia.”

3.3-Million- Year-Old Stone Tools Found in Northern Kenya

In May 2015, researchers announced the discovery of 3.3-million-year-old stone tools found at a site in Kenya, making the idea that tool-making predated all Homo species more acceptable. If it turns tools are indeed tools, the species that made them is unknown although some scientists have speculated it was Australopithecus afarensis (Lucy). Scientists detailed their findings in the May 21, 2015 issue of Nature. Charles Q. Choi of Live Science wrote: “The 3.3-million-year-old stone artifacts are the first direct evidence that early human ancestors may have possessed the mental abilities needed to figure out how to make razor-sharp stone tools. The discovery also rewrites the book on the kind of environmental and evolutionary pressures that drove the emergence of toolmaking. [Source: Charles Q. Choi, Live Science, May 20, 2015]

Until now, the earliest known tools were about 2.8 million years old, the researchers said. The artifacts are by far the oldest handmade stone tools yet discovered — the previous record-holders, known as Oldowan stone tools, were about 2.6 million years old. "We were not surprised to find stone tools older than 2.6 million years, because paleoanthropologists have been saying for the last decade that they should be out there somewhere," Harmand said. "But we were surprised that the tools we found are so much older than the Oldowan, at 3.3 million years old."

“It remains unknown what species made these stone tools. They could have been created by an as-yet-unknown extinct human species, or by Australopithecus, which is currently the leading contender for the ancestor of the human lineage, or by Kenyanthropus, a 3.3-million-year-old skull of which was discovered in 1999 about a half-mile (1 kilometer) from the newfound tools. It remains uncertain exactly how Kenyanthropus relates to either Homo or Australopithecus. "Sometimes the best discoveries are the ones that raise more questions than provide answers," study co-author Jason Lewis, a paleoanthropologist at Stony Brook University and Rutgers University in New Jersey, told Live Science. "In any of these cases the story is equally new and interesting. We are comfortable not having all of the answers now."

“The stone tools were discovered in the desert badlands of northwestern Kenya, where the arid, rocky terrain resembles a New Mexican landscape. The artifacts were found next to Lake Turkana in 2011 almost by accident. "We were driving in the dry riverbed and took the left branch instead of the right, and got off course," Harmand said. "Essentially, we got lost and ended up in a new area that looked promising. Something was really unique about this place, we could tell that this zone had a lot of hidden areas just waiting to be explored." By the end of the 2012 field season, excavations at the site, named Lomekwi 3, had uncovered 149 "Lomekwian" stone artifacts linked with toolmaking. "It is really exciting and very moving to be the first person to pick up a stone artifact since its original maker put it down millions of years ago," Harmand said.

“The researchers tried using stones to knock off and shape so-called flakes or blades — a process known as knapping — to better understand how these Lomekwian stone artifacts might have been made. They concluded the techniques used may represent a stage between the pounding used by earlier hominins and the knapping of later toolmakers. "This is a momentous and well-researched discovery," paleoanthropologist Bernard Wood, a professor of human origins at George Washington University, who was not involved in the study, said in a statement. "I have seen some of these artifacts in the flesh, and I am convinced they were fashioned deliberately." Analysis of carbon isotopes in the soil and animal fossils at the site allowed the scientists to reconstruct what the vegetation there used to be like. This led to another surprise — back then, the area was a partially wooded, shrubby environment.”

Implications of 3.4-Million-Year-Old Tools

Oldawan tool, about 2 million years old

Charles Q. Choi of Live Science wrote: “Chimpanzees and monkeys are known to use stones as tools, picking up rocks to hammer open nuts and solve other problems. However, until now, only members of the human lineage — the genus Homo, which includes the modern human species Homo sapiens and extinct humans such as Homo erectus — were thought capable of making stone tools.[Source: Charles Q. Choi, Live Science, May 20, 2015]

If early hominins were using tools so early, that means their cognitive abilities were also more advanced than previously thought, Briana Pobiner, a paleoanthropologist at the Smithsonian Institution, told Live Science. For instance, humans' closest living relatives, chimpanzees, may crack nuts using stones or may sharpen sticks to hunt other primates called bush babies, but they do that with their teeth. Making stone tools involves bashing one stone on another rock to make the desired pointy shape. "To make a stone tool, you use a tool to make a second tool," Pobiner told Live Science.[Source: Tia Ghose, Live Science, August 20, 2015 |]

That's a different cognitive process, she said. "There's a lot of planning and forethought involved," Pobiner said, from picking the right kind of rock, to striking with the tool in just the right way to get the stone flaked off. Either way, the new study, combined with the discovery of similarly aged tools in Kenya, make the notion that ancient human ancestors cut the Dikika bones much more likely, Pobiner said. |

Revised Theory of Toolmaking

Oldawan chopper

Charles Q. Choi of Live Science wrote: “Conventional thinking has been that sophisticated toolmaking came in response to a change in climate that led to shrinking forests and the spread of savannah grasslands. Stone blades likely helped ancient humans get food by helping them cut meat off the carcasses of animals, given how there was then less food such as fruit to be found in the forest. However, these findings suggest that Lomekwian stone tools may have been used for breaking open nuts or tubers, bashing open dead logs to get at insects inside, or maybe something not yet thought of. "The Lomekwi 3 evidence suggests that important evolutionary changes that would later be really important for Homo to survive on the savannah were actually evolving beforehand, in a still-wooded environment," Lewis said.[Source: Charles Q. Choi, Live Science, May 20, 2015]

This discovery also has implications for understanding the evolution of the human brain, researchers said. Toolmaking required a level of dexterity and grip that suggests that changes in the brain and spinal tract needed for such activity could have evolved before 3.3 million years ago. "The capabilities of our ancestors and the environmental forces leading to early stone technology are a great scientific mystery," Richard Potts, director of the Human Origins Program at the Smithsonian's National Museum of Natural History, who was not involved in the research, said in a statement. The newly dated tools "begin to lift the veil on that mystery, at an earlier time than expected."

“The scientists are now looking at the surfaces and edges of the tools under microscopes and with laser scans to try to reconstruct how they were used, "and also studying the sediment in which they were found to search for trace elements or residues of any possible plant or animal tissues that could be left on them after use," Harmand said. The site is still under excavation, and Harmand said other artifacts could exist from early attempts at knapping. "We think there are older, even more rudimentary, stone tools out there to be found, and we will be looking for them over the coming field seasons," he added.”

Are Hobbits Evidence That Australopithecus Left Africa?

The origin of Homo floresiensis (the hobbits of Indonesia) raises some interesting questions, one being that they could be descendants of predecessor of homo erectus —homo habalis or even a Australopithecus species — and this in turn could mean homo habalis or Australopithecus species could have emerged from Africa before Homo erectus.

Deborah Netburn wrote in the Los Angeles Times: “One hypothesis posits that Homo floresiensis descended from the large-bodied hominin Homo erectus that lived between 1.89 million and 143,000 years ago. Scientists say it is possible that Homo erectus may have arrived on Flores from Java, perhaps after being washed out to sea by a tsunami. Over time, this species began to shrink on its new island home – a relatively common phenomenon known as island dwarfism. “Lots of animals that end up on islands get smaller for a variety of reasons like limited food sources, or because there are no large predators to stay big for,” said Karen Baab, a paleoanthropologist at Midwestern University in Glendale, Ariz., who was not involved in the study. “We even see it in modern humans in certain environments that are home to pygmy populations.” [Source: Deborah Netburn, Los Angeles Times, June 8, 2016 */]

“The other hypothesis states that Hobbits descended from smaller and more ancient hominins like Australopithecus africanus or Homo habilis that were already diminutive at the time they reached the island. Both theories have challenges. One might accept that Homo erectus grew smaller in stature by two-thirds over time. After all, a smaller body is easier to feed. But for some scientists, it is hard to believe that it made evolutionary sense for its brain to shrink by half. Losing brain power doesn’t seem like a likely evolutionary development. On the other hand, if you buy that Homo floresiensis was descended from Australopithecus or Homo habilis, then you have to explain how either of these species made their way to Indonesia when their remains have never been found outside of Africa. */.

A bone study published in 2017 in the Journal of Human Evolution showed there was nothing to support claims that Homo floresiensis evolved from Homo erectus, which scientists say was an ancestor of modern humans, and thus did not have any direct links modern humans. Teeth similarities had been suggested as evidence that homo erectus and hobbits were linked.

Melissa Davey wrote in The Guardian: “The study, led by the Australian National University researcher Dr Debbie Argue from the school of archaeology and anthropology, found there was no evidence Homo floresiensis evolved from the much larger Homo erectus, the only other early hominin known to have lived in the region. It was one of several theories about the origins of the “hobbit” species. Since it was discovered, researchers have tried to determine whether Homo floresiensis was a species distinct from humans. [Source: Melissa Davey, The Guardian, April 21, 2017]

“The findings add support to the theory that the species evolved from one in Africa, most likely Homo habilis, and that the two species shared a common ancestor. It was possible that Homo floresiensis evolved in Africa and migrated, or the common ancestor moved from Africa and then evolved into Homo floresiensis somewhere, the researchers concluded. Prof Mike Lee of Flinders University and the South Australian Museum used statistical modelling to analyse the data collected by the researchers. He said the findings were clear. Homo floresiensis occupied a very primitive position on the human evolutionary tree,” Lee said. “We can be 99 percent sure it’s not related to Homo erectus and nearly 100 percent it isn’t a malformed Homo sapiens.” |=|

There is a good evidence that a relatively large human that lived 700,000 years ago and shrunk quickly and stayed that size ago is an ancestor of Homo floresiensis according to two studies published in Nature in June 2016. Marlowe Hood of AFP wrote: “A modest haul of teeth and bones from an adult and two children has bolstered the theory that Homo floresiensis arrived on Flores island as a different, larger species of hominin, or early man, probably about a million years ago. And then, something very strange happened. These upright, tool-wielding humans shrank, generation after generation, until they were barely half their original weight and height. [Source: Marlowe Hood, AFP, June 9, 2016 \^/]

Image Sources: Wikimedia Commons except Laetoli footprints from Sciencephoto and Dikika bones from Wired

Text Sources: National Geographic, New York Times, Washington Post, Los Angeles Times, Smithsonian magazine, Nature, Scientific American. Live Science, Discover magazine, Discovery News, Times of London, Natural History magazine, Archaeology magazine, The New Yorker, Time, Newsweek, BBC, The Guardian, Reuters, AP, AFP and various books and other publications.

Last updated September 2018

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