Author: heartofbonesblog

Gentle Giants of Madagascar

Madagascar is like a look into the past. Because it split from mainland more than a

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Lemurs are old but there not That old. Still liked the movie as a kid.

million years ago, the ecology has lived in isolation allowing ancient species to leave descendants up to modern day. It’s because of this isolation that about 90% of all life on of Madagascar’s is endemic. It’s why Lemurs are alive today and not anywhere else on earth because Madagascar lack the suborder Haplorhini( monkeys, apes, and humans) which out competed them millions of years. And the reasons lorises bush babies, and pottos ( suborder Strepsirhini that includdes lemures) survived in pockets around the world is because of there nocturnal lifestyles that allow them to be active at night instead of the other suborder. So, if you ever thought Lemurs and lorises looked ancient you most definitely would have been right. Also because of there time in a evolutionary isolation from the rest of the world Lemurs have become incredible with a lack of predication and ability to take advantage to all the diverse ecosystems Madagascar had to offer. One of the most interesting finds that have stunned paleontologists are a family called the sloth lemurs or Palaeopropithecidae, which I still can’t pronounce.

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sloth lemurs on the left. Modern day lemurs on the right corner.

They are interesting not because they are related to sloths. Which even to this day I still don’t know why that name stuck. It’s because of there enormous size that no living lemur can compete with. But like modern lemurs based on the fossil record they where extremely diverse. Varying in size and shape, one even having the skull the size of a gorilla and must have weighed a couple hundred pounds. But, for there size these giants

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Archaeoindris fontoynontii, the biggest lemur found yet.

dentition shows they all had vegan diets, eating on mostly fruits and leafs. And based on there size and the fossil record there most likely was never a lot of them living at once per generation, but  some of the species did live to only a couple thousand years ago. They most likely where very close to their habitat making them less adaptable to sudden changes in the environments. And there is some evidence of climate change in parts of Madagascar as well as early human settlements in regions that used agriculture to change the environment around them. There is even fossil evidence of these large lemurs with cut marks on their bones, signs of butchery for either their meat or fur. So the extinction of these animals might have been from human of the environmental change but well probably never know.

On a brighter note. A few years ago now there was a discover of sloth lemur fossils found in  Tsimanampetsotse National Park. Some of the finds had complete skeletons which will help to understand more about there anatomy.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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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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Mitochondrial Eve

The title might be a little misleading for it doesn’t show the first woman in our species, but the most recent mitochondrial ancestor of all humans and everyone today is a decedent from her. But what is mitochondrial DNA? It’s separate DNA outside of the nucleus that located in, you guessed it, the organelle mitochondria. And it doesn’t recombine like nucleic DNA so when it is pasted down through the generation it undergoes very little change. The way mtDNA works is it’s pasted through the maternal line given to daughters and sons, but the her sons significant other will only pass down mtDNA to there children from her own maternal line.

But why is there DNA in mitochondria in the first place? Well it goes far back when there was only single celled organisms and instead of digesting smaller bacterium these single celled organisms made a symbiotic relationship where instead of being digested were copied in the cells reproduction cycle and the first mitochondria where small bacterium. The theory that explains this endosymbiotic theory that is accepted by most scientists today.

MtDNA also lead to whats is called haplogroups, which can look at your ancient ancestry as well as migration of past human populations. The way it works is people in a haplogroup can trace that specific mtDNA to a common ancestor. The changes in mtDNA are created by a mutation and each of these changes in the mtDNA is a different haplogroup.  Not everyone has the same mutations in the mtDNA because these mutations happened in different geographical locations at different times. And using mtDNA and archaeological evidence it can be used to track human migration. One example is a person in Northeast Asia can have the same haplogroup found in Native Americans showing a common ancestry among them that created that haplogroup in Asia. And around 15,000 years ago people in Asia migrated to Alaska with the same Haplogroup.

But since mtDNA shows a portion of ancient ancestry you most likely wont find a lost family member if you learn a stranger has the same haplogroup as you since haplogroups origins can be thousands of years old.

 

https://blog.23andme.com/23andme-and-you/haplogroups-explained/

 

Smaller Brains

For most of human evolution there has been about a 2 million year anatomical-reflectiontrend for bigger brains. But in the last 20,000 years there has been quite a reversal on that ancient trend.  And I’m not pulling a fast one on you, for a time this was only a known fact among paleoanthropologist, and they notice this trend despite what region of the world or demograph. And when biologists and geneticists learned about this trend they were as surprised as anyone that our specious are loosing grey matter. It does make sense though that anthropologists specifically paleoanthropologists would recognize this trend since they are likely the only field that looks at contemporary human anatomy to millions of year old fossils and skulls.

Based on skeletal analysis of skulls from 20,000 years or before the average volume of someones brain was around 1500cc (cubic centimeters) and today that has dropped to around 1350cc. That’s about the size of a tennis ball! And as I said this trend is happening everywhere, Europe, Asia, Africa you name it. Simply put by anthropologist Christopher Stringer “It’s Strange.” And for now no one really knows why this trend started or whether a smaller brain is inherently bad or will lead to less intelligence. But there are some studies that are trying to understand this trend.

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One studied suggest that the development of complex societies lead to a decrease in brain size. As society became more complex and spread the workload there was no need for a big brain to us your wits and try to survive. Civilization became like a social safety net.

One study measured the skulls of Europeans from the Bronze age around 4000 years ago to the medieval times. This research got similar data that as populations increased and society got more complex the trend of smaller brains continued. But the study suggest a smaller but smarter brain. Because a bigger brain takes so much energy to keep functioning, it already takes up about 20% of all calorie intake. So the goal is a smaller but smarter brain. And over the past 20,000 years there have been adaptive mutation related to brain development and neurotransmitter systems that changed the inner working of our brains, but to what extent no one knows. Though they could have affected our temperament and reasoning abilities.

One Study states that it isn’t to do with intelligence but rather the selection against aggression. And that in a way we domesticated ourselves or became more tame. Like all the other animals we have domesticated their brain size has gotten smaller and so more tame than there wild counterpart.

But so far we can only see the changes of our evolution but not where it’s taking us. By anthropologist Stringer “it’s perfectly plausible our modern brain is smarter in some ways, dumber in others, and more docile overall.”

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For more information:

http://discovermagazine.com/2010/sep/25-modern-humans-smart-why-brain-shrinking

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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