Category: Paleoanthropology

The Importance of Turkana Boy

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Turkana Boy or KNM-WT 15000 was discovered in 1984 by Richard Leaky’s team in Kenya. He would prove to be a very important find, being around 40% complete having most of its skull, long bones and hips. And bases on his osteology I would say that him and Homo erectus where not that different from us the neck down, and explain his species importance to us. Here is why.

Neck down he had a body plan that was almost exactly like our. He was only around eight or nine when he died but based on the bones and teeth the species had a slightly faster growth rate then us. But even at eight he was around 5 foot 3 and still growing. His hips where shaped like ours and he also had long legs and shorter arm like us suggesting that he was completely bipedal and his species being adapted completely to the  ground. Fossilized footprints from another member of his species dates back around 1.5 million years ago proving that they had a similar gait and stride to us and that they were capable of long distance walking and running.

Based on Turkana Boy they also had adapted to the very dry hot climate of East Africa. He had a narrow slender body with long legs and arms. This reflects what is called the Bergman Allen rules. Which can be seen in, especially mammals, species around the world. The hotter dryer environment to help dissipate heat its better to have longer limbs(Allen) and slender shoulders and hips(Bergman). You can still see this in modern day humans living in the opposite extreme environments like the Inuits of North America or the aboriginals of Australia.

I can also make some assumptions about their physiology. I think Turkana Boy and Homo erectus had the adaptive cooling mechanism to sweat. Sweating had to of originated in the hot dry environments of Africa. This type of cooling mechanism doesn’t make sense in a hot humid environment because there is to much water in the air already for sweat to evaporate efficiently to get rid of heat. It defiantly doesn’t make sense for it to originate in a cold environment. His long limbs also reflect that with longer limbs means more sweat glands and ability to effectually stay cool in a very dry environment. And if they had sweating as a cooling mechanism they would also have been hairless one the body similar to today. Because for sweating to work there skin would need more exposure to the sun so sweat can effectively evaporate taking heat with it. One last assumption, if they were sweating and had less body hair their skin would need protection from the sun and they mostly likely had abundant amount of melanin. And with this strong selective pressure to be protected from the intense UV rays of the sun they would have had dark skin.

To modern day we are still very much bipedal. We are still the “hairless apes.” And even though I don’t like it on a humid Midwestern summer day we are also still able to sweat which might have all started with our ancestors like Turkana Boy.

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The Homo habilis body plan?

The specious was first discovered by the Leaky’s in 1960 at Olduvia Gorge in Tanzania Africa. Since then with more fossil discoveries we know they lived 2.5 to 1.5 million years ago and they used oldowan stone tool tradition. They also, compared to austrolopiths, had a smaller face but bigger brains measuring around 650 cubic centimeters(cc). Compared to australopiths brain case found around low 500 cc. And for awhile the only fossils found were skulls and teeth giving no indication on what there body plan looked like. Until around 1986 at Oduvia Gorge the fossil remains labeled as OH 62 were found which had the partial remains of both upper and lower limbs. And based on the partial limbs it indicated a more primitive body plan still being bipedal but with longer arms then legs.

 

But some still find it controversial that the lack in complete limbs can’t indicate it’s limb proportions properly. But based on the most recent study published on Homo floreseens they shared a common ancestor with Homo habilis being a sister lineage. Because we have a fairly complete skeleton of the hobbits with complete limb bones with limb proportion of short legs and long arms. And because they were related closely and the Hobbits still had a primitive limb proportions like that of the austrolopiths it can be argued Homo habilis had the same body plan. And even though they were different species and had different traits and adaptions, the general body plan doesn’t change nearly as much with closely related species. Take us for example, we are closely related to Neanderthals and Denisovans sharing a common ancestor. Though we are different species we all have the same body plan to be bipedal. Or take all the monkey on our planet. There are many far and wide with different adaptations to there environment but they all have the same body plan to be arboreal quadrupeds with all limbs at the same length, even baboons who are terrestrial. Because of the new evidence showing both Homo habilis and the hobbits being closely related it can be argued that for a fact Homo habilis even though a handy man was bipedal with short legs and long arms.

 

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Hot off the Press: Homo naledi’s Birthday.

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In 2013 there was a trove of hominin fossils in quantity unlike anything discovered before. The fossils would be discovered in South Africa in Rising Star Cave deep underground ,40 m to be exact, having to crawl and climb in uncomfortable compact space until they reached there treasure chamber Dinaledi. There, lead by Lee Berger, they collected over 1500 pieces of bones and at least 15 individuals ranging in age from infancy to old adulthood and there are still bones there to be further excavated!

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Left to Right: AU afarensis, Homo erectus, Homo naledi.

With examination of the bones it was certain they were in our own genus Homo and became the species Homo naledi. The Homo naledi was a interesting mosaic of human and primitive feature. They had a very small sized brain about the size of a large orange, and a more ape-like thorax/ shoulders. Their feet and ankles were defiantly made for bipedal locomotion and almost indistinguishable between ours. And they had longer leg bones then Australopiths, with a more human gait. Their hands and hips are an odd blend of both homo and austhralopiths. Their hands had shorter fingers and a long opposable thumb for power grip, but also curved fingers remnant of the austhralopiths. You could draw a line across their hips, the upper portion looking like Australopithecus afarensis, but the lower half looking a lot more human.

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Rising Star site.

But how old are they? They have had trouble putting a date to these bones. Mostly because they where found in mixed soil and not rock, like hominins in East Africa that allowed them to be dated. There was also no animal fossils to be found to put a relative date on them. But until very recently, on April 25 to be exact, Lee Berger announced that the bones only date back around 300,000 to 200,000 years ago. And that the methods and data to reach that conclusion will be disclosed in the next following weeks. So what does this new data mean? Well it most likely means that there is no direct ancestral connection between Homo naledi and us because the split between Australopiths and early Homo would be around 3 million years ago. But it still could be a early Homo originating around 2 million years ago but remaining unchanged and persisted becoming a relic of a specious still with quite a few primitive feature that are 2 million years old.

There is still more that can be done to further understand this specious. They are exploring a second chamber that has uncovered three more individuals. They are also trying to extract DNA from the bones but have so far become unsuccessful. But If they did it would reveal a lot more about the species and possibly, if it is a relic specious, information about australopiths, but that could be wishful thinking.

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Then there’s the mystery of them being in Dinaledi chamber in the first place. They didn’t live there or there would be animal bones or possibly flint tools. They weren’t prey because there are no signs of any of the 15 individuals being mauled by a big African cat. They weren’t rushed in there by a flood or there would be other animals or rocks/rubble or plants that would have been deposited as well. But there is only them and fine grain soil that covers the bottom of the tomb. With all the other known alternatives not possible Bergers team has come to a rather extreme conclusion that these are signs of ritualistic burial. Saying the distribution of the bones suggest they have been placed there over a long period of time. And that it was unlikely that that many individuals like mothers with infants and very old individuals would just go in and get lost or stuck and die. There are obviously critics of this idea, most professionals don’t support it, and it is true the team has shown no evidence of this kind of complex behavior, only eliminated the other alternatives. For now this remains a big puzzle.

More Information: Just keep in mind that the new data on the age doesn’t support the idea that they are right at the base as a 3 million year old Homo species.

http://www.pbs.org/wgbh/nova/evolution/dawn-of-humanity.html  : a good documentary by nova broadcast by PBS about the discovery and findings at Rising Star and also a bit on human evolution,

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Web Sites:

http://www.bbc.com/news/science-environment-39710315

http://www.timeslive.co.za/scitech/2017/04/28/Homo-naledis-a-youngster-at-just-250%E2%80%9A000-years%E2%80%9A-say-surprised-scientists

https://www.theguardian.com/science/2015/sep/10/new-species-of-ancient-human-discovered-claim-scientists

http://news.nationalgeographic.com/2015/09/150910-human-evolution-change/

Hobbits of Middle Earth

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In 2004 the world would be reintroduced to a species that actually sounds like a work of fiction. Homo floresiensis was discovered in 2003 in a limestone cave Liang Bua in Indonesia on the island of Flores. The fairly complete skeleton found would be labeled LB-1 and she only would have stood 1 m tall with a brain about 1/3 as big as ours and also had some big (Hobbit) feet compared to her overall size and short legs. Because of their small size and they were ironically discovered the same year the last installment of the Lord Of the Rings Movie came out they were given the name Hobbits. LB-1 lived around 80,000 years ago and even though they had a small brains they still made tools which were also discovered with LB-1 that date back between 190,000 and 50,000 years ago. They hunted pygmy elephants large rats (which are still alive today) and coped with Komodo dragons.

 

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The reason they are so small was thought to be Island dwarfism. Which simply put are adaptions to use less energy because they are in a island setting with limited resources and few predators. Which allow for island dwarfism adaptations which generally put selective pressure for a smaller stature and brain which takes a lot of calories to keep up. Even the pygmy elephants they hunted are also examples of island dwarfism. But a lot of questions remained. Is she actually a separate species or a diseased modern human? What is their ancestry, and did they evolve on Flores or a neighboring  island? Also, how did they get to the island in the first place?

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It would take more than a decade after the initial discovery to find more hominin bones in Flores. The discovery took place at Mata Menge where they discovered a partial mandible and some teeth. They looked remarkable similar to LB-1 but nearly as complete as LB-1 but they still had major significance because they date to be about 700,000 years old meaning they lived on the island for more than half a million years! The age blew the modern human theory out of the Shire, for they truly were their own species. There were still a lot of questions that could only be answered with more fossils.

 

hobbit-humanSince 2003 there has been much debate about the mysterious Homo florensiensis. Its ancestory has been a fierce topic. The main group believing it’s ancestor was Homo erectus experienced island dwarfism when they got isolated on the island of Flores, but there hasn’t been fossil evidence on the island. Others see features that are older in the hobbits that lead them to suggest there ancestor is actually Homo habilis or earlier austhrolopiths. But based on the most comprehensive analysis ever done for the hobbits that published in mid April of this year suggests strongly that they evolved form a unknown primitive ancestor from Africa. The hobbits are a sister lineage with Homo habilis sharing a common ancestor. And either the hobbits ancestor migrated out of Africa ,before Homo erectus left Africa, and they evolved outside of Africa or they stayed in Africa and evolved and then later migrated still before Homo erectus. And Most likely the hobbits were able to survive as long as they did because they were isolated in Flores which shows no evidence of Homo erectus of ever discovering. But eventually they did go extinct about 50,000 years ago either from a volcano eruption that happened around then or when we discovered the island around the same time.

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A Bite into the Past

Between 4 million to 1 million years ago there was a a very diverse group of bipedal hominins in East and South Africa called the australopiths. There are currently 9 specious of australopiths discovered and several of them lived concurrently at a time. They can be divided into two groups, the more gracile generally having a smaller build and a more generalized diet. While the robust have a tank of a skull that was very specialized for the food consumption in their niche. And based on there teeth between the two groups they had a very diverse diet that most likely varied between species. But what changed in Africa gave rise the the first hominin and would eventually lead to us?

Before 4 million years ago in Africa there were prevalent rainforests with species similar in morphology in the skull and diet to modern day African apes, gorillas, and chimps. Chimps and gorillas spend half of there waking hours chewing on mostly fruits and high fibrous plants. The shape of there molars with thin enamel are used for sheering there food and large canines used to peel the hard exterior of fruit. But by the epoch of the Pliocene(5.3-2.6 million years ago) there was this ongoing trend of the earth becoming cooler which made Africa drier. During the australopiths era, the cooling made wide spread open wood lands and grasslands. Which greatly diminished and scattered limited fruit. This would lead australopiths to a diet of less nutritious diet of leaves, stems, seeds, and also tubers and roots, and bulbs(which were year round and can survive droughts). With the change in the environment and a change in the opportunity of less nutritious foods would have strong selective pressure for adaptations to obtain the nutrients from there varying diet. Also because they had such a varied diet compared to the their ape counter parts, and lived in varying environments creating new niches creating a very diverse (textbook adaptive radiation) radiating genus separated into the two groups of gracile or robust Australopithecus.

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Because of the hard, less nutritious, and fibrous foods they where primarily eating, unlike chimps in the rain forest, natural selection acted strongly on the components of mastication (chewing) to breakdown foods into smaller particles to easily get more nutrients. The components mostly changed for the adaptations to eat the new African environment are the shape, size, and thickness of teeth, jaw muscles, jaw bones, the maxilla and mandible.

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There was big push for big grinding posterior teeth for there type of chewing that could withstand the endlessly repetition of powerful chewing and be able to bite forcible with out damaging the teeth. The forceful chewing also created thick molar enamel that could withstand the chewing. There was also a trade off for smaller canines as they weren’t being used as usefully as their ape counter part who used them for peeling tough fruit. You can see this progressive trade off from earlier australopiths who had bigger canines then the later specious of the genus. Apes also have thinner molar enamel and higher cusps in there molars for sheering there food unlike australopiths who grinded their food with thick enamel and flat molars.

Jaw Muscles

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They needed large jaw muscles to be able to chew so forcefully on their food. The robust australopiths are the extremists in this category for they had such large temporalis muscles they had a boney crest called a sagital crest for more muscle. They also had widely expanded zygomatic arches that some robust austslopiths faces were as wide as it was long. The expansion was for more room for the masseter chewing muscles.

Jaw bones

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There jaw bones, maxillas, and mandible, were also under selective strain to be tougher so that they didn’t fracture under strain which would be game over if you could noteat. So their jaws  developed to be thicker, taller, and wider to lower the stress of chewing forcible to obtain the nutrients in there diet.

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Donald Johanson. The Discoverer of Australopithecus afarensis (Lucy)

 

 

Legacy:

Gracile australopiths would eventually lead to the genus Homo and the robust became extinct probably because their more specialized adaptations lead to a less flexible diet as climate change continued in Africa. Even today we still have a reflection of what the australopiths left as we became there decedents. Like a more diverse diet less dependent on fruit, adaptations that was continued as we developed into our more specialized bipedal moment, grinding chewing as we chew with thick molar enamel, and small incisor-like canines.

For more information

The Story of the Human Body by Daniel Lieberman

http://kcur.org/post/dental-detectives-what-fossil-teeth-reveal-about-ancestral-human-diets#stream/0

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Footprints after the ash

A volcano erupts. Soon after tephra fall covers the surrounding terrain creating a thin layer of ash. During the eruption light rain fell causing the ash layer to a gooey mud. Animals walk through this terrain of mud leaving footprints. Fast forward 3.6 million years and what you have is preserved fossilized footprints. The preservation was made possible because the ash in the mud is wet carbonatite, which once dried hardens into a rock-hard substance. This event took place in now Laetoli Tanzania. The site was discovered in in 1976, lead by Mary Leaky, but it wasn’t until 1978 the the site would become world famous as the Laetoli Footprints, for they had discovered hominin footprints for the first time, also the oldest hominin footprints to date. But not just any footprints. These looked strikingly similar to us because we do this all the time on our own feet. These were snapshot actions of bipedal locomotion, walking on two legs.
1258847_e15982324c_bThis really was a revolutionary find. Because the leading consensus, developed in the 1800’s when the hominin fossil record was scarce, was that the initial kick start to humanity was larger brains and intelligence. But based on the expanded fossil record it was bipedalism as the initial fundamental behavior of hominin, not intelligence that came first and would eventually separate use from our closest relative the apes.

First Steps: What are feature that contribute to bipedal locomotion based on the prints?

2010657e6d99431c9c4d942253c771ecThere are many adaptions that contribute to the use of being able to walk on two feet. One example is our foramen magnum, a hole on our skull that connects to our erect spine. While apes have theirs in a posterior position for being on all fours most of the time. But what can we learn from observing the feet for bipdelism? Quite a lot! There are quite a few observations that can be made, but two main feature of bidality that are the the longitudinal foot arch and the lack of an opposable big toe. If you feel the bottom of your foot you can feel an arch and what that is suppose to do is be like a shock absorber when making contact with the ground and also give you leverage when pushing forward. Apes have flat feet, which reflect the adaptation of their feet for grasping. Apes have a divergent big toe which can be used for terrestrial walking and grasping objects. Humans don’t have a divergent big toe, because our feet are solely (pun intended) specialized for for walking and running.

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The Laetoli footprints were most likely made by Australopithecus afarensis as fossils were found later near the site in the same sedimentary layer as well as in other parts of East Africa where they have been discovered. Observing the foot prints, recent studies of them using computer models, and examination of the fossils themselves resolves any doubt that A.U. afarensis was bipedal. The footprints show that they had foot arches, and no divergent big toe. The features also show they had a similar gait, manner of walking, compared to modern humans as their foot hit the ground first, heel-strike, and ending with the toes pushing off the ground, toe-off. The closeness of the footprints show a short stride meaning that the had short legs compared to archaic and modern humans.

For more information:

http://discovermagazine.com/2015/oct/19-first-impressions

http://humanorigins.si.edu/evidence/behavior/footprints

 

Leakey’s in Africa

1500x675_leakeysFor Most of the 20th century and into the 21st century there has been a family working in some of the most desolate parts of the world changing our understanding of what it means to be human, and changing the face of paleoanthropology. Paleoanthropology is the study of human evolution which includes the excavation and examination of hominid and hominin fossils, ancient stone tool, and other paleontologist evidence for a further understanding of our origins. And with the major contribution of the Leakys’ and other anthropologists they were able to debunk the held beliefs that humans evolved in Europe or Asia, a simple straight line of human evolution from earliest to modern, humans had recent ancestry, and the brain expanded as humans evolved and then eventually walked upright. Each was eventually disproved. But not easily and not quickly. And the contribution of the Leakys’ have helped paved the way to further understanding by setting up a fossil record of hominins in East Africa.

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Louise Leakey in Kenya

It is hard to quantify the contribution Louis Leakey made to paleopanthropology and science. Throughout his life he wrote 20 books and 150 articles about paleo, anthropology as well as the pros and cons of British imperialism in Kenya. He was born and grew up in Kenya. His parents were English missionaries to the Kikuyu tribe. He was a happy kid that made friends with the other kids in the Kikuyu tribe, some of whom where for his entire life. By the age of thirteen he actually became a member of the Kikuyu tribe. Later in life he was actually tasked with recording the traditions and history of the Kikuyu tribe. His love from an early age for animals and prehistory would set him on a career course for anthropology. And while looking for animals he discovered ancient tools that inspired his belief in African origins. He would later get his education in England. which proved hard at first since the education system in Kenya was different. And for a time he was an outsider since he came from a different part of the world. He would eventually get his degrees in anthropology and archaeology from Cambridge University. And for the rest of his life he would fossil and stone tool hunt for further understanding of our past. Facing much opposition at the time for his position on human ancestry in Africa would prove true under scientific scrutiny and Africa was eventually placed as the birthplace of humanity.

 

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Mary leaky is a world renowned hominin fossil hunter. And is credited with many discoveries that sharked the understanding of human evolution at the time. She was a well accomplished women for her time and she didn’t even graduate from high school! She was born in England in 1913, then Mary Nicol. Her parents were artists and they lived a nomadic lifestyle around Europe. Her father loved archaeology and prehistory and he would take her to museums, paleolithic sites like cave paintings, and would even take her to sites they could participate in and found paleolithic tools and blades. This influenced her to seek a career in archaeology. She would get expelled from numerous schools and by the end was left to her own devices. She would seek her own education and informally attend lectures in London about archaeology and participate in archaeological digs. She proved her artistic ability was useful for being the illustrator of anthropologists books by drawing the stone tools and other artifacts found. At a dinner party after the Royal Anthropological Institute a friend of Mary introduced her to Louis so she could possibly be the illustrator of his next book. This would start a long relationship, both personally and professionally.

Their entire career now would be focused on East Africa in the Great Rift Valley. The area

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Australopithecus boisei or “Nutcracker Man”

is unique because of the divergent plates that border and created the Red Sea. The plates movement (faults) would eventually make the Great Rift Valley and expose sedimentary layers (strata) that are millions of years old. Three major sites the Leakey team discovered or used would put Africa on the map for human origins. Olduvai Gorge proved invaluable in understanding human evolution. Tools like Oldowan (used by Homo habilis and possibly by later Australopithecus) and Acheulean (used by Homo erectus). And the discovery Australopithecus boisei and the earliest species in our genus  Homo habilis. Ologesailie had a wealth of Acheulean tools. The fossils of animals found there indicate they where butchered with the aid of these hand axes. And based on the one hominin discovered there ,decades after Louis and Mary were there, they were made by Homo erectus and they did not live there where they made the tools and butchered the animals for their meat. And the site of Laetoli which proved to be Marys most exiting discoveries where the 89 foot long trail of preserved footprints of animals (some extinct like the three toed horse) but also of human footprints! They where dated to be 3.6 million years putting the timetable back for when our ancestors first practiced in bipedal locomotion.

 

Legacy:

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Richard And Louis Leakey

This is just a small glimpse on how Louis and Mary put Africa on the map for human origins. And how they brought inspiration to future anthropologists and laid a path for future paleoanthropologists to interpret there discoveries as science progresses and the fossil record increases.

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Leakys’ Angles

As their name grew and they could acquire funding from there success, Louis also helped assist other anthropologists by supporting them and offering funds to support there research. One popular example are Leakey’s Angles. Three primatologists Jane Goodall, Dian Fossey, Birute Galdikas. Leakey wanting to know more about existing hominids and there behavior, and apply to what the behavior might have been to extinct hominids and hominins.

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Meave and Louise Leakey

One of their three sons Richard Leakey followed in his parents footsteps along with his wife Meave to make spectacular findings in places like Turkana Basin, where his team discovered an almost complete Homo erectus called Turkana Boy. Richard and Meave’s daughter, Louise, today continues the Leakey tradition and is a paleoanthropologist in East Africa.

Composite image of historic footprints.
“One small step for man.” Neal Armstrong