Tuesday, June 02, 2020

Homo erectus 200,000 Years Older Than We Thought

UPI has a story about a discovery in South Africa of a Homo erectus infant that is 200 ky older than the oldest known specimen currently in existence.  From the original Science article
Fossil hominins from South Africa are enriching the story of early human evolution and dispersal. Herries et al. describe the geological context and dating of the hominin-bearing infilled cave, or palaeocave, at a site called Drimolen in South Africa (see the Perspective by Antón). They focus on the age and context of a recently discovered Homo erectus sensu lato fossil and a Paranthropus robustus fossil, which they dated to ∼2.04 million to 1.95 million years ago. This makes Drimolen one of the best-dated sites in South Africa and establishes these fossils as the oldest definitive specimens of their respective species ever discovered. The age confirms that species of Australopithecus, Paranthropus, and early Homo overlapped in the karst of South Africa ∼2 million years ago
The goofy thing about this is that, in East Africa,  early Homo was still running around and out-competing the robust australopithecines (Paranthropus).  The fossil was uncovered and described over a five year period at the site of Drimolen, which is part of the UNESCO World Heritage Site in South Africa that contains the important fossil sites of Swartkrans and Sterkfontein. 

From the UPI story:
“One of the questions that interests us is what role changing habitats, resources, and the unique biological adaptations of early Homo erectus may have played in the eventual extinction of Australopithecus sediba in South Africa,” said study co-author Justin Adams, researcher at Monash University's Biomedicine Discovery Institute.
“Similar trends are also seen in other mammal species at this time. For example, there are more than one species of false sabre tooth cat, Dinofelis, at the site -- one of which became extinct after two million years,” Adams said. “Our data reinforces the fact that South Africa represented a truly unique mixture of evolutionary lineages -- a blended community of ancient and modern mammal species that was transitioning as climates and ecosystems changed.”
Just a few short years ago, it was thought that Australopithecus sediba might be ancestral to early Homo based on the characteristics of its hands, pelvis and the proximity of stone tools to the Rising Star Cave.  This was an idea championed by Lee Berger, but it now seems likely that it was another, earlier form that gave rise to Homo erectus

Here is the photo of DNH134, taken by Jesse Martin, Reanud Joannes-Boyau, and Andy I. R. Herries



Monday, June 01, 2020

Oldest Evidence of Siberian Crossing of Native Americans

UPI has a story about evidence from around Lake Baikal that links populations of Siberia to the earliest groups who came over from Siberia to the New World.  Brooks Hays writes:
New genomic analysis of ancient remains in Siberia -- detailed this week in the journal Cell -- have offered scientists fresh insights into the movements of human populations across Eurasia and into the Americas at the end of the Stone Age.

“Previous studies observed the genetic differences between individuals from different time periods, but didn't investigate the differences by dating the admixture events,” lead study author He Yu, postdoctoral researcher at the Max Planck Institute for the Science of Human History in Germany, told UPI in an email. “Our study reports a 14,000-year-old individual, which actually fills in a large blank of ancient genomes in this region, between 23,000 and approximately 8,000 years ago.”
By using the DNA of a tooth from the 14 ky old individual, Yu and his team have established links to the earliest Native Americans.
“The deep connection observed in this study is sharing of the same admixed ancestry between Upper Paleolithic Siberian and First Americans," Yu said. "We are not suggesting interbreeding between Native American and Siberian, or any back flow of Native American ancestry into Siberia. But we are suggesting that, the First American ancestry was formed in Siberia and also existed there, in a large range of time and space, so we can detect it in ancient Siberian individuals.”
There have always been conflicting theories about how and when the migrations to the New World occurred and there has always been evidence for movements from the Lena River, in Siberia and the northern Amur river in northern China.

Interestingly, they also found genetic evidence of the plague in some of the Bronze age populations from the area, which they hypothesized came from Europe, indicating that there was considerable movement between these populations.

Tuesday, March 17, 2020

BioLogos: Approaching Adam

BioLogos has a post on how to approach the teaching of the historical Adam aimed specifically at parents as they talk to their kids. Christy Hemphill writes:
If your kids are hearing a young earth creationist perspective at church or a Christian school, they may find those ideas very appealing and convincing for a time. Depending on your situation and personality, you may have to be careful not to put your kids in the middle of your own power struggles or debates with other adults in your lives. Kids need space and time to build their worldviews and figure stuff out for themselves. If you consistently model openness to questions and how to seek out reliable information to answer them, that will pay off. But at the end of the day, it will be your honesty and unconditional acceptance that will make you trustworthy to your kids, not the strength of your answers and arguments.

The other issue she discusses is something that rears its ugly head in my household regularly:
Most parents in the American context have to decide how to handle Santa Claus in their family. If you are one of the families that introduces the idea of Santa Claus to your children as make believe from the beginning, you probably still don’t want your kids to make themselves a persona non grata by ensuring every other kid in preschool is clued in. The analogy breaks down, of course, especially if you believe that Adam and Eve are historical figures, but most parents don’t want their kids to alienate others or be ostracized in some way for having different insights into Genesis than their peer group. What do you do when all your kids’ cousins, or friends from Sunday School, or classmates at the homeschool co-op are being taught something very different about Adam and Eve and the origins of humans?
I have been open with my kids about the fact that I am an evolutionary creationist and accept not just an old universe but evolution as it pertains to all life, including humans. We have not had a really good conversation about Adam and Eve because my thoughts are not concrete on this issue. While it is possible they were real people, it is clear from the account in Genesis that the entire episode is stylized, geographically truncated (what was happening on the rest of the planet at that time?) and reads like myth.  John Walton argues that the story is presenting theological truths at the expense of literal facts and that it mirrors other accounts of creation at that time period.

Dennis Venema presents some strong genetic evidence that the human population could never have been below the effective size of 10,000 and was likely much larger.  The other issue is the source for the original Mitochondrial Eve and Male Y chromosome.  As he puts it:
Current estimates place mitochondrial Eve just after the dawn of Homo sapiens as recorded in the fossil record, at about 180 KYA. This places her within our species. Until recently, Y-chromosome Adam was dated later, at about 50 KYA, the time of significant human migration out of Africa. Recently, however, a rare Y-chromosome variant has been found in modern humans that pushes back the last common ancestor of all human Y-chromosome DNA to approximately 210 KYA – which, interestingly enough, is right at the cusp of our own species as recorded in the fossil record. Since our species arose as a continuous population that gradually diverged from other hominins, there is no reason to expect that all of our DNA variation will come back to a common ancestor (or coalesce, to use the technical term) within our species. Indeed, some of our regular chromosomal variation does not coalesce within our species or even as far back as our common ancestral population with chimpanzees.
The problems for the literal Adam begin to mount very quickly and it becomes hard to make sure that you don't kill a child's faith with these nagging bits of evidence.

This is a thorny topic because it cuts to the beginning of the Bible and how we understand the notion of original sin.  As far as the historical Adam and Eve being the first people, the science since is unclear.

Sunday, March 08, 2020

FFRF Lodges Complaint Against New York School Teacher

First, I wish the Freedom From Religion Foundation would go away.  They are poisoning the discourse between religion and society by being militantly atheistic and intolerant.

Having said that, it all began when a parent sent them a letter with this in it:
It said that biology teacher Phil Lucason told students that when they take the Regents Exam, they will have to “play the evolution game, where evolution is the answer to everything.” He explained that none have been “able to find when something becomes something else” and that evolution is contrary to genetics, such as if a dog “underwent several mutations and became a cat.”

Lucason also reportedly told his class that polar bears could mutate among themselves from brown fur to white fur, but that the eye, for example, could never have evolved because of its complexity and the necessity for a series of mutations.

“So, what that means is that you have to play the evolutionary game because the people writing this are married to that idea, despite the new proofs and the science coming out,” he is quoted as saying about the exam.
IF that account is accurate (might be a big “if”) then that science teacher has absolutely no business teaching science, because he has a very poor understanding of it and ZERO understanding of evolutionary theory.  If he is reading the ICR and AiG, then he is not staying current with science.

Teaching creationism straight-up, is unconstitutional, hence the attempts to “teach the controversy,” “explore the strengths and weaknesses” and so on.  This will not end well for the school district and the teacher. 

Saturday, March 07, 2020

David MacMillan Writes OpEd Blasting Creationism, Ken Ham Fires Back

David MacMillan, a former creationist, wrote an opinion/editorial for the Lexington Herald Leader, in which he blasted the Ark Encounter and creationism in general. The posts center around the film “We Believe in Dinosaurs,” an expose of the inner dealings of the Creation Museum and Ark Encounter.  About Ken Ham,  he wrote:
“We would be thrilled to see a major economic impact for the town, but…that town’s central business area is on the opposite side of the interstate from the Ark Encounter, half a mile from that interstate, and currently has no major hotels or restaurants.”

In other words, it’s Williamstown’s own fault that they’re not benefiting from the Ark. If they had given Ham land closer to downtown, instead of a whole half-mile away, perhaps things would be better. To hear Ken Ham tell it, they were fools to ever trust him.

Ham’s claim is not only insulting, but disingenuous. Far from actively supporting the community that opened its coffers to his organization, Ham has repeatedly acted to enrich the park at the town’s expense. Although the Ark Encounter is incorporated as a for-profit LLC in order to take advantage of tourism tax incentives, Ham has claimed that the non-profit status of the parent company should excuse them from paying city taxes that support firefighting and other essential services.
This has, evidently, been a sore subject for people and has been chronicled by the Herald-Leader here. MacMillan finishes his piece thus:
As a science advocate, I take strong issue with the nonscience Ken Ham peddles to families and students. His parody of the scientific method does real harm, bleeding inexorably into education and public policy. The whole-hearted embrace of “alternative facts” and the rejection of plain evidence are making our society more and more polarized. Yet Ken Ham’s treatment of Williamstown is a reminder that these sorts of cult-like organizations have impacts that go much farther than the foolish ideas they promote.
Here is how Ham responded:
Much of the film was based on old information; filming started in 2013. Originally, we were told by the producers that they were doing a documentary emphasizing the creative side of making museum exhibits. Despite assurances to the contrary, the producers created a heavily biased, error-filled film designed to sway viewers to a specific conclusion and does not rise to the level of a real documentary. In December 2016, a controversial filmmaker joined the project and helped fund it, taking it into a decidedly mocking direction. Subsequently, we revoked their media access and declined any future interviews.
I have not had a chance to see the film so cannot comment on Ham's accusations here.  Ham remarks in his opinion piece that it made perfect sense to the city to sell the land that the Ark Encounter sits on to Ham and company (Ark Encounter, LLC).  Oddly missing from Ham's piece, however is that the state of Kentucky rescinded $18 million dollars of tax incentives and that, three days later, Ham sold the land back to his non-profit entity, Crosswater Canyon, for $10.  Suspicion was that this sale was to get out of paying $700,000 in taxes.  Peter J. Reilly, of Forbes Magazine, suggested that this was not nearly as nefarious as it sounded, however, but was simply clumsy and unethical.

Expect more fireworks from this.  

Sunday, March 01, 2020

Neandertal/Denisovan Ancestors Interbred With Unknown Hominin

As if the tangle of early archaic Homo sapiens relationships couldn't get any more confusing, evidence has now surfaced that the ancestors of both the Neandertals and Denisovans interbred with a hominin only known from its DNA signature.  From the University of Utah, through Science Daily:
For three years, anthropologist Alan Rogers has attempted to solve an evolutionary puzzle. His research untangles millions of years of human evolution by analyzing DNA strands from ancient human species known as hominins. Like many evolutionary geneticists, Rogers compares hominin genomes looking for genetic patterns such as mutations and shared genes. He develops statistical methods that infer the history of ancient human populations.
According to the article, Rogers performed a study that argued that Neandertals and Denisovans separated earlier than has previously been suggested but that his evidence for this was thin.
The new study has solved that puzzle and in doing so, it has documented the earliest known interbreeding event between ancient human populations -- a group known as the "super-archaics" in Eurasia interbred with a Neanderthal-Denisovan ancestor about 700,000 years ago. The event was between two populations that were more distantly related than any other recorded. The authors also proposed a revised timeline for human migration out of Africa and into Eurasia. The method for analyzing ancient DNA provides a new way to look farther back into the human lineage than ever before.

"We've never known about this episode of interbreeding and we've never been able to estimate the size of the super-archaic population," said Rogers, lead author of the study. "We're just shedding light on an interval on human evolutionary history that was previously completely dark."
According the Rogers, the DNA evidence puts the final nail in the coffin of the complete Out-of-Africa replacement model of modern human origins:
The researchers also proposed there were three waves of human migration into Eurasia. The first was two million years ago when the super-archaics migrated into Eurasia and expanded into a large population. Then 700,000 years ago, Neanderthal-Denisovan ancestors migrated into Eurasia and quickly interbred with the descendants of the super-archaics. Finally, modern humans expanded to Eurasia 50,000 years ago where we know they interbred with other ancient humans, including with the Neanderthals.
This was likely something like Homo antecessor.  As is also true with the Chinese evidence, this evidence suggests that throughout human evolutionary history, there has never/rarely been a time when these groups of archaic and early modern Homo sapiens could not/did not interbreed. As J. Lawrence Angel once said “When two groups of people meet, they may fight, but they will always mate.”

The Science Advances article is open access. 

http://dx.doi.org/10.1126/sciadv.aay5483

Saturday, February 29, 2020

Evolution of the Human Foot

Nature News has an interesting examination of how the human foot evolved the arch, the singular most important aspect in the ability to perform bipedal locomotion.  Glen Lichtwark and Luke Kelly write:
Humans evolved to walk and run effectively on the ground using two feet. Our arched foot, which is not a characteristic of other primates, is a unique feature crucial for human bipedalism. The arch provides the foot with the stiffness necessary to act as a lever that transmits the forces generated by leg muscles as they push against the ground. The arch also retains sufficient flexibility to function like a spring to store and then release mechanical energy. Writing in Nature, Venkadesan et al.1 present a new view of how foot stiffness is regulated. Their finding not only has exciting implications for understanding foot evolution, but also provides a possible framework when considering foot health and how to design better footwear.
The authors note that there are two different arches present in the human foot, the longitudinal arch, which is more familiar to people and the transverse arch. They argue that the transverse arch (across the top of the foot) is as important for walking as the longitudinal arch. The authors note that the transverse arch has been neglected in sports and medicine and that more research needs to be done in this area. 

Thursday, February 27, 2020

Humans in Asia survived Toba super-eruption 74,000 years ago

Chris Clarkson and company have produced a study arguing that the super volcano Toba eruption of 74,000 years ago did not lead to a population bottleneck in Asia, as has been suggested.  Brook Hays of UPI writes:
For the study, scientists analyzed evidence of human populations and climate change across a significant stratigraphic record -- a column of rock and sediment layers comprising 80,000 years of history -- from the Dhaba dig site in northern India's Middle Son Valley.

The column yielded stone artifacts suggesting Middle Palaeolithic tool-using populations were present in India prior to the Toba eruption.

"Although Toba ash was first identified in the Son Valley back in the 1980s, until now we did not have associated archaeological evidence, so the Dhaba site fills in a major chronological gap," researcher J.N. Pal, professor of ancient history and archaeology at the University of Allahabad in India, said in a news release.
The authors argue that there are stone tools at the Dhaba site the strongly resemble Middle Stone Age tools in Northeast Africa. The occupation levels go down to 48,000 years ago, where Levallois and microlithic tools are found. This suggests continuous occupation of the site by different groups with similar stone tool technologies.

Time to chuck another theory into the dustbin of history.  

Thursday, February 13, 2020

The Ghost of an Unknown Hominin

Science Alert has a story about the Ghost of an Unknown Hominin in Africa.  Carly Cassella writes:
The gene pool of modern West Africans contains the 'ghost' of a mysterious hominin, unlike any we've detected so far. Similar to how humans and Neanderthals once mated, new research suggests this ancient long-lost species may have once mingled with our ancestors on the African continent.

Using whole-genome data from present-day West Africans, scientists have found a small portion of genetic material that appears to come from this mysterious lineage, which is thought to have split off from the human family tree even before Neanderthals.
It is not clear to me that these necessarily represent different species. This may reflect an inter-related group of populations from a very genetically diverse population. As my advisor Fred Smith once upon a time said: “If two species interbreed on a regular basis, is it reasonable to call them different species?”

BTW, the  “Unrelated” skull in the page is the Kabwe skull from What was once Rhodesia, discovered in 1925, 400 feet down, in a mine.