Scientists revise timeline of human origins

Jul 03, 2014
Between 2.1 and 1.8 million years ago, the oldest known species of the human genus, Homo, exhibited diverse traits. These species include the 1470 Group and the 1813 Group, based on the Kenyan fossils KNM-ER 1470 (left) and KNM-ER 1813 (second from left), respectively. By 1.8 to 1.9 million years ago, the species Homo erectus had evolved in Africa and started to spread to Eurasia. Early populations of this long-lived species are represented by the Kenyan fossil KNMER 3733 (right) and the Georgian fossil Dmanisi Skull 5 (second from right). The three lineages -- the 1470 group, the 1813 group, and Homo erectus -- overlapped in time for several hundred thousand years. The Kenyan fossils, from the site of Koobi Fora in the Lake Turkana region of Kenya, are housed in the National Museums of Kenya. Fossils from Dmanisi are housed in the Georgian National Museum. Credit: Kenyan fossil casts – Chip Clark, Smithsonian Human Origins Program; Dmanisi Skull 5 – Guram Bumbiashvili, Georgian National Museum

Many traits unique to humans were long thought to have originated in the genus Homo between 2.4 and 1.8 million years ago in Africa. Although scientists have recognized these characteristics for decades, they are reconsidering the true evolutionary factors that drove them.

A large brain, long legs, the ability to craft tools and prolonged maturation periods were all thought to have evolved together at the start of the Homo lineage as African grasslands expanded and Earth's climate became cooler and drier. However, new climate and fossil evidence analyzed by a team of researchers, including Smithsonian paleoanthropologist Richard Potts, Susan Antón, professor of anthropology at New York University, and Leslie Aiello, president of the Wenner-Gren Foundation for Anthropological Research, suggests that these traits did not arise as a single package. Rather, several key ingredients once thought to define Homo evolved in earlier Australopithecus ancestors between 3 and 4 million years ago, while others emerged significantly later.

The team's research takes an innovative approach to integrating paleoclimate data, new fossils and understandings of the genus Homo, archaeological remains and biological studies of a wide range of mammals (including humans). The synthesis of these data led the team to conclude that the ability of early humans to adjust to changing conditions ultimately enabled the earliest species of Homo to vary, survive and begin spreading from Africa to Eurasia 1.85 million years ago. Additional information about this study is available in the July 4 issue of Science.

Potts developed a new climate framework for East African human evolution that depicts most of the era from 2.5 million to 1.5 million years ago as a time of strong climate instability and shifting intensity of annual wet and dry seasons. This framework, which is based on Earth's astronomical cycles, provides the basis for some of the paper's key findings, and it suggests that multiple coexisting species of Homo that overlapped geographically emerged in highly changing environments.

Hominin evolution from 3.0 to 1.5 Ma. Green: Australopithecus, Yellow: Paranthropus, Red: Homo. The icons indicate from the bottom the first appearance of stone tools at ~2.6 Ma, the dispersal of Homo to Eurasia at ~1.85 Ma, and the appearance of the Acheulean technology at ~1.76 Ma. The number of contemporaneous hominin taxa during this period reflects different strategies of adaptation to habitat variability. The cultural milestones do not correlate with the known first appearances of any of the currently recognized Homo taxa. Credit: Antón et al., Science, 2014

"Unstable climate conditions favored the evolution of the roots of human flexibility in our ancestors," said Potts, curator of anthropology and director of the Human Origins Program at the Smithsonian's National Museum of Natural History. "The narrative of human evolution that arises from our analyses stresses the importance of adaptability to changing environments, rather than adaptation to any one environment, in the early success of the genus Homo."

The team reviewed the entire body of fossil evidence relevant to the origin of Homo to better understand how the human genus evolved. For example, five skulls about 1.8 million years old from the site of Dmanisi, Republic of Georgia, show variations in traits typically seen in African H. erectus but differ from defining traits of other species of early Homo known only in Africa. Recently discovered skeletons of Australopithecus sediba (about 1.98 million years old) from Malapa, South Africa, also include some Homo-like features in its teeth and hands, while displaying unique, non-Homo traits in its skull and feet. Comparison of these fossils with the rich fossil record of East Africa indicates that the early diversification of the genus Homo was a period of morphological experimentation. Multiple species of Homo lived concurrently.

"We can tell the species apart based on differences in the shape of their skulls, especially their face and jaws, but not on the basis of size," said Antón. "The differences in their skulls suggest early Homo divvied up the environment, each utilizing a slightly different strategy to survive."

Even though all of the Homo species had overlapping body, brain and tooth sizes, they also had larger brains and bodies than their likely ancestors, Australopithecus. According to the study, these differences and similarities show that the human package of traits evolved separately and at different times in the past rather than all together.

Evolutionary timeline of important anatomical, behavioral and life history characteristics that were once thought to be associated with the origin of the genus Homo or earliest H. erectus. Credit: Antón et al., Science 2014

In addition to studying climate and fossil data, the team also reviewed evidence from ancient stone tools, isotopes found in teeth and cut marks found on animal bones in East Africa.

"Taken together, these data suggest that species of early Homo were more flexible in their dietary choices than other species," said Aiello. "Their flexible diet—probably containing meat—was aided by stone tool-assisted foraging that allowed our ancestors to exploit a range of resources."

The team concluded that this flexibility likely enhanced the ability of human ancestors to successfully adapt to unstable environments and disperse from Africa. This flexibility continues to be a hallmark of human biology today, and one that ultimately underpins the ability to occupy diverse habitats throughout the world. Future research on new fossil and archaeological finds will need to focus on identifying specific adaptive features that originated with early Homo, which will yield a deeper understanding of .

Explore further: Biology of early human relative uncovered

More information: Evolution of early Homo: an integrated biological perspective, by S.C. Antón et al. Science, 2014. www.sciencemag.org/lookup/doi/… 1126/science.1236828

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KBK
1.4 / 5 (26) Jul 03, 2014
It's kinda difficult to accept anything that mainstream or 'acceptable to present to the unwashed masses' system presents to us.

The number of anomalies that are rejected, denied, fought over, ridiculed to outright destroyed (reputations and lives destroyed) (entire archeological sites, data, and finds purposely destroyed/hidden) makes passive acceptance of mainstream archeology completely unacceptable to an aware and thinking human.

There so many anomalies and so much data being denied, whole cloth, that again, anything that mainstream archeology says is probably so inaccurate that it's not worth bothering with.

~~~~~~~~~~~
The most careful look at mainstream archeology finds it to be a cover story for a reality that systems of elitism and power don't want the general public to look at, or per chance - to begin to understand.

It is a damning conclusion that is inevitably arrived at by the intrepid explorer of information - information that lies beyond the general facade.
Vietvet
4.4 / 5 (25) Jul 03, 2014
@KBK

Another nutty conspiracy rant.
Drou
1.4 / 5 (10) Jul 03, 2014
Why do anthropologist continue to think in straight lines? Surely it is apparent that there were hundreds of varieties of 'Homo' most of whom just flourished for a short time then disappeared. Modern humans are a composite from a small collection of anthropoids that managed to survive for a time before being replaced by an improved 'strain'. In short it is an exercise in futility to even try to create a family tree for the evolution of modern humans because so many past contributors to our lineage have gone without a trace.
Given that the time line for the first anatomical human is continually being pushed back in time, why is the question never asked i.e. If humans have been around for a million years, why did it take so long for civilised development to begin. Both Neanderthal and Cro-magnon had larger brains than modern humans, nature does not go in reverse, so is modern man the runt of evolutionary development inferior to other varieties of humans?
Torbjorn_Larsson_OM
4.7 / 5 (14) Jul 03, 2014
Interesting. But FWIW the Homo species at 2.3 million year is contested AFAIK. 1-2 arguable finds with arguable dating.

@KBK: I assume it can be confusing to read the latest, cutting edge, in any topic. What is the current size of transistors in integrated circuits. What is the best jet engine today. Et cetera.

But the basics, perhaps dated 1-2 decades but then also firm, is well hashed out and presented in digestible form. E.g. Wikipedia is usually a good start.

Your remaining comment of trolling science ("anomalies", "cover story") is based on personal incredulity and conspiracy theory (which is a neat trick to combine!) and as such useless fallacy respectively crackpotism. "A nutty rant" is a suitable description.
Torbjorn_Larsson_OM
4.6 / 5 (14) Jul 03, 2014
@Drou: The sociology of anthropology is complex, let us not go into that. It is very hard to map fossils, of which there will be scant data, to genomes and so populations. The trees are known to be bushy, but Homo is exceptionally so, and it is a late discovery. (Yet not "hundreds" of variants as you suggest, we have no evidence for that.)

We are lucky though, we have even scarcer data on chimp evolution.

As the article shows, "civilized" development started before Homo as regards the tool and food use that continues yet today. In fact, since the one distinguishing hominid character is a small canine, our history is nothing but self-socialization. We are the meek monkey (except when compared with bonobos).

Nature go in reverse all the time, parasites are simplified and ~ 40 % of animal species. The shrunken brain of modern man suggests that large societies are much simpler lifestyles than small group hunter-gathering. We are dumber, because we can be.
flashgordon
2.3 / 5 (3) Jul 03, 2014
@KBK

Another nutty conspiracy rant.


Haven't you noticed, this Physorg is full of conspiracy people including those who make the articles; I once saw a meteorite shower renamed the tears of Saint Jerome!
JVK
1 / 5 (15) Jul 03, 2014
Biological and social feedback mechanisms are complexly entwined in the context of nutrient-dependent pheromone-controlled ecological adaptations.

Ecological variation in nutrient availability and the metabolism of nutrients to species-specific pheromones that control the physiology of reproduction in species from microbes to man attest to the likelihood that all aspects of evolutionary theory will soon be abandoned.

They will be replaced with accurate representations of cell type differentiation by amino acid substitutions, which are manifested in the morphological and behavioral phenotypes of all animal species.

Nutrient-dependent pheromone-controlled ecological adaptations: from atoms to ecosystems
http://figshare.c...s/994281
Rustybolts
1.2 / 5 (17) Jul 04, 2014
"I assume it can be confusing to read the latest, cutting edge, in any topic"
"Another nutty conspiracy rant. "

What's with all the A-holes bullying people over there opinion? Seams like it's the same jerks all the time. KBK made a valid point. There is stuff that's out of the norm being tossed out and never looked at again. It's the way it works! If you want to put something down on paper just to prove your doing your job that's the way it has to work. Otherwise you'll be stumped for years and never publish anything. This is the same reason why it CHANGES all the time, they didn't get it correct the first time. Please stop the 12 year olds from bullying peoples opinion! Prove your smart by listening and not by trying to make others look stupid.
Vietvet
4.8 / 5 (17) Jul 04, 2014
@Rustybolts

KBK did not make a single valid point! He accuses entire branches of science of hiding, destroying and/or ignoring evidence without even offering a single bit of proof. He has to do better if he expects any credibility on this site.
Egleton
1 / 5 (6) Jul 04, 2014
I dont like a long list of declaritive statements presented as an argument.
eg "The moon is made of green cheese." "No it is not", "Yes it is."

What I wonder is where does the Ape/Pig cross happen?
I anticipate volley of empty, declaritive statements in response.
no fate
1 / 5 (12) Jul 04, 2014
@Rustybolts

KBK did not make a single valid point! He accuses entire branches of science of hiding, destroying and/or ignoring evidence without even offering a single bit of proof. He has to do better if he expects any credibility on this site.


Credibility on this site...good one. How is that judged again? The most "5's" means the opinion is credible?

If you want to find out how messed up some of the branches of science are, talk to scientists. Don't judge based on your own idealistic interpretation of it. Or are you the last Vietvet standing that still has faith in the establishment to act in it's citizens best interest?
Surly
5 / 5 (9) Jul 04, 2014
@no fate: It's judged by having had a college science education (or a middle school one, which is enough to contradict a lot of the bullshit you hear here) and being able to recognize good evidence.
What I wonder is where does the Ape/Pig cross happen?
I anticipate volley of empty, declaritive statements in response.

It didn't. John Hewitt's fine on chemistry stories, but can't recognize when a statement about genetics is bull.
no fate
1 / 5 (7) Jul 04, 2014
@no fate: It's judged by having had a college science education (or a middle school one, which is enough to contradict a lot of the bullshit you hear here) and being able to recognize good evidence.
What I wonder is where does the Ape/Pig cross happen?
I anticipate volley of empty, declaritive statements in response.

It didn't. John Hewitt's fine on chemistry stories, but can't recognize when a statement about genetics is bull.


Surly: Agreed regarding evidence. Letters after your name don't make you right, as evidenced by alot of the bullshit you hear here...and everywhere else. Example, how many politicians have degrees?
yep
1 / 5 (6) Jul 05, 2014
Is not ManBearPig evidence enough?
JVK
1 / 5 (9) Jul 05, 2014
Molecular mechanisms for the inheritance of acquired characteristics—exosomes, microRNA shuttling, fear and stress: Lamarck resurrected?
http://journal.fr...133/full

Also see my comments on the article:

In my model, there is no need for theoretical predictions, since nutrient-dependent changes in the microRNA/messenger RNA balance lead to amino acid substitutions that differentiate cell types and the metabolism of nutrients to species-specific pheromones controls biodiversity via conserved molecular mechanisms, which link ecological variation to ecological adaptations.

Nutrient-dependent/pheromone-controlled adaptive evolution: a model. http://www.ncbi.n...24693353

A single nutrient-dependent base pair change and amino acid substitution is all that's required to differentiate the cell types of chimps, gorillas, and humans. That fact has been known for 40-50 years (Dobzhansky 1964; 1973).
JVK
1 / 5 (9) Jul 05, 2014
http://www.ncbi.n...24939910

Excerpt: "There are genes that do not fit into the conventional coding/non-coding narrative in the non-coding set. Several genes are annotated as potentially non-functional but may actually be functional under certain conditions."

My comment: If nutrient-stress and social stress did not cause non-functional genes to become functional, ecological variation could not result in ecological adaptations via nutrient-dependent pheromone-controlled amino acid substitutions that are the epigenetically effected determinants of cell type differentiation in all individuals of all species.

Others might then need to continue considering the pseudoscientific nonsense of neo-Darwinism, which is what many people seem to prefer to do. They've been taught to believe in it, and can't stop believing in nonsense -- even after realizing how ridiculous their beliefs are.
Bob Osaka
not rated yet Jul 06, 2014
(sigh) Well, it looks like we all just got older.
marc verhaegen
1 / 5 (1) Jul 09, 2014
Antòn-Potts-Aiello suppose that "the success & expansion of the genus [Homo] rested on dietary flexibility in unpredictable environments", but several recent publications ( anatomical, embryological, physiological, nutritional, paleontological & paleo-environmental data) suggest Homo's early Pleistocene intercontinental expansion be explained by a dispersal along African & Eurasian coasts + venturing inland from the coasts along the rivers: at coasts, rivers & wetlands, they collected (through bipedal wading & beach-combing & diving) shallow aquatic & waterside plant & animal foods, which contained the necessary brain-specific nutrients for brain expansion (e.g. long-chain poly-unsaturated fatty acid DHA). Only coastal dispersal can account for brain expansion, long & straight legs, broad bodies & pelvises, large & linear bodies, stone tools, diet of animal foods, pachyostosis etc., see
www. researchgate. net/ profile/ Marc_Verhaegen
independent. academia. edu/ marcverhaegen
Captain Stumpy
5 / 5 (3) Jul 09, 2014
Credibility on this site...good one. How is that judged again? The most "5's" means the opinion is credible?
@nofate
aren't you glad that is not how it is judged?
Credibility is in the PROOF offered. See Surly's post to you.
Or are you the last Vietvet standing that still has faith in the establishment to act in it's citizens best interest?
logical fallacy and appeal to conspiracy
I distrust the gov't more than anyone, but I am educated enough to learn science and judge what is real science vs pseudoscience
Example, how many politicians have degrees?
another logical fallacy, attempt at misdirection and irrelevant, no matter how true
IMHO-politicians are crooks
BUT
they are also NOT scientists... so cannot offer evidence here (and that means the idiot Gore too)
Captain Stumpy
5 / 5 (3) Jul 09, 2014
In my model, there is no need for theoretical predictions, since nutrient-dependent changes in the microRNA/messenger RNA balance lead to amino acid substitutions that differentiate cell types and the metabolism of nutrients to species-specific pheromones controls biodiversity via conserved molecular mechanisms, which link ecological variation to ecological adaptations
@jk
but in your keyboard diarrhea and prolific posting history, you also make claims that mutations cannot cause diversity or evolution, which is proven wrong by your own model because your own model causes mutations and you keep telling everyone that it supports diversity

So, logically, when you support a model that CAUSES mutations, but then try to denigrate Evolution, which is supported by YOUR OWN MODEL then it makes one wonder what you are REALLY trying to do

so... perhaps you would like to clarify that here?
if your model causes mutations, why are you always speaking out against mutations?
JVK
1 / 5 (4) Jul 09, 2014
The conserved molecular mechanisms of sensing and signaling link ecological variation to ecological adaptations in all species. For example, nutrient-dependent pheromone-controlled cell type differentiation links species diversity in C. elegans and P. Pacificus, a nematode with morphological differences (teeth) and behavioral differences.

Dissecting the Signaling Mechanisms Underlying Recognition and Preference of Food Odors
http://www.jneuro...tml?etoc