Saturday, September 30, 2017

Did Humans Become a Distinct Species 350, 000 Years Ago?

The hits just keep on coming.  On the heels of the discovery in Morocco, at Jebel Irhoud, of a skull with some modern characteristics dated to 315 thousand years ago, we now have a genetic study that proposes that our species emerged between 350 and 260 thousand years ago.  How did a genetic study reveal this?  Science News reports:
The trick was retrieving a complete version of the ancient boy’s DNA from his skeleton to compare with DNA from people today and from Stone Age Neandertals and Denisovans. Previously documented migrations of West African farmers to East Africa around 2,000 years ago, and then to southern Africa around 1,500 years ago, reshaped Africans’ genetics — and obscured ancient ancestry patterns — more than has been known, the researchers report online September 28 in Science.
The ancient boy’s DNA was not affected by those migrations. As a result, it provides the best benchmark so far for gauging when Homo sapiens originated in Africa, evolutionary geneticist Carina Schlebusch of Uppsala University in Sweden and her colleagues conclude.
In line with the new genetically derived age estimate for human origins, another team has proposed that approximately 300,000-year-old fossils found in northwestern Africa belonged to H. sapiens (SN: 7/8/17, p. 6). Some researchers suspect a skull from South Africa’s Florisbad site, dated to around 260,000 years ago, qualifies as H. sapiens. But investigators often place our species’ origins close to 200,000 years ago (SN: 2/26/05, p. 141). There is broad consensus that several fossils from that time represent H. sapiens.
What is important to understand is that we have the fossils from Herto and Omo that date to between 150 and 200 thousand but that does not mean that is the earliest time that our species may have actually showed up. The Jebel Irhoud material is only partly modern—in the face mostly—and we do not know how the genetics for this population would look. It is possible that, as some investigators are saying, the Jebel Irhoud material represents the earliest fossil representation of our clade and that over the next 100 thousand years, the modern form fully evolved.   

Q&A With Lee Berger on Human Evolution

The Sunday Times has an interview with Lee Berger about human evolution, in advance of his new book, co-written with John Hawks, Almost Human: The Astonishing Tale of Homo naledi and the Discovery That Changed Our Human Story. As was reported earlier, the original fossils were undated but appeared to be reflective of an early stage in the development of Homo. This idea was shattered when new dates were derived.  As I wrote at the time:
Homo naledi, however, was missing a date—until recently. Nearly everyone in the scientific community thought that the date of the Homo naledi fossils, when calculated, would fall within the same general time period as other primitive early Homo remains. We were wrong. The radiometric dates—recorded using several methods carried out at different laboratories—yielded almost identical ages of between 236 and 300 thousand years before the present (BP). This was an order of magnitude younger than we expected. To say we were surprised would be an understatement.
Interestingly, the interviewer asks no important questions about Homo naledi or the Dinaledi Star cave, itself.  Amid all of the sturm und drang of his tortuous relationships with Ron Clarke and Philip Tobias (✟ 2012), there is one interesting question about human evolution in general:
Throughout the final chapters of the book you often mention how much there still is to learn about Homo naledi and that it’s very likely that there are more early hominim species which are yet to be discovered. The skeletal material you recently came across in the Lesedi Chamber shares similarities with Homo naledi and adds to this statement. What can/does this new discovery tell us about human evolution in Africa?

I think the clear picture that has come from both the discovery of Australopithecus sediba and Homo naledi is that the story of human evolution is not a simple, linear, straightforward one but that ours is a complex history. Naledi and sediba show us that there is more to be found – it’s clear that we don’t really know their ancestral history and the few fossils of other species found across Africa don’t help us much with interpreting where they fit in our family tree – and that’s exciting. We currently are back in the Dinaledi and Lesedi Chambers and making new discoveries – particularly exciting is we seem to have strong evidence that Homo naledi did indeed come down the narrow chute the way our “underground astronauts” come – and that is wonderful and hard to explain – but it’s exciting!
This has been a contentious issue: whether or not the fossil remains were “placed” there or were brought in by scavengers. What is also not clear is if the book was published before the new dates became available, or not.  I will have to buy the book to find that out.  While the rest of the interview is a tad unsubstantive, it is interesting.

Friday, September 29, 2017

Five Peculiar Fossils

Colin Barras of The New Scientist has a very short, very peculiar article on five hominin fossils that have been used to define new species and addresses the validity of each in very cursory fashion.  The strength of the article is in the links that it provides.  About Sahelanthropos, he writes this:
Features at the skull’s rear suggest it sat atop a vertical spine like that of a human, hinting that S. tchadensis walked upright. To make sure, other fossils will be needed – particularly from the legs. Unconfirmed reports suggest that a thigh bone was found with the skull, but this has not yet been discussed in a scientific paper. With so little evidence to go on, some are sceptical that S. tchadensis can really yet be defined as a hominin rather than some other form of ape – yet.
These are the least of its problems, as it is likely a surface find. Aside from this, when Wolpoff and colleagues examined the cranial base, here is what they found:
The prominence of the nuchal muscles, so important in head balance and loading, and shoulder movements, is enhanced by the significant development of the tuberculum linearum. The point is not that the TM 266 cranial rear and posterior portion of the cranial base was unlike hominids because the region looks like apes, but that TM 266 had a posture that is not upright because the region reflects nuchal functions similar to those of apes.

The foramen magnum - orbit plane angle does not directly address posture or locomotion in these hominoid primates (contra Zollikofer et al., 2005). Without a key postcranial element such as a pelvis or femur, none of these data provide compelling evidence for upright posture or obligate bipedal locomotion, and the various details of the nuchal plane argue against it. This functional implication has a phylogenetic consequence—by itself it is sufficient to disprove the phylogenetic hypothesis that TM 266 was a hominid.
This isn't skepticism. This is the door slamming shut.  It can be a surface find and still be a Miocene ape. In my recent piece for BioLogos, it did not occur to me to include this fossil since there are so many problems with it.  At this point, in Africa, the earliest reasonable evidence we have for hominins is Orrorin tugenensis

Read the whole (short) thing.

Thursday, September 28, 2017

Neandertal Child Gives Clues to How They Developed

Gizmodo is running a story about the discovery and examination of a Neandertal child, from El Sidrón Cave, in Spain, who died under mysterious circumstances:
The first step was to determine the chronological age of death by performing a dental analysis. The specimen, dubbed El Sidrón J1, exhibited a mix of baby and adult teeth. Incremental markings on the teeth, which are counted like rings on a tree, showed that the boy died at 7.7 years of age. The skeletal remains exhibited no signs of trauma, no signs of sickness, or any other physical abnormalities. El Sidrón J1, aside from experiencing an untimely death, appears to have been a perfectly normal and healthy Neanderthal child.

The researchers then compared the skeleton’s biological stage of development with what would be expected in a modern human of the same age. To their surprise, they found few differences between the two human subspecies in terms of the pace of growth.

“The comparison...indicate(s) that there was no noticeable difference in the growth and maturation of this Neanderthal juvenile in comparison with modern human juveniles,” said study co-author Luis Rios, a Member of the Paleoanthropology Group at Museo Nacional de Ciencias Naturales, at a press conference held yesterday.
Research has generally shown that Neandertals developed a bit more quickly than modern humans but, in one critical area, this study did not back up that claim.
Perhaps more significantly, analysis of the Neanderthal skull shows that El Sidrón J1's brain was roughly 87.5 percent the size of an average adult Neanderthal at the time of death. The brains of modern humans, on the other hand, reach 95 percent the size of an adult at that age. Previous studies have suggested that the larger brains of Neanderthals underwent rapid growth during these formative years, yet this new research would seem to contradict such claims.
There is a bit of circularity going on here, though because the child is being aged based on dental development and, if for some reason, the dental development does not completely track with either the current estimates or there were some developmental insults, the age might be off.  This is speculation on my part, though.  In any event, it gives us more to understand the developmental biology and ontogeny of these very, very close relatives.  

Wednesday, September 20, 2017

Forbes: Ark Encounter Local Tax Scandal Not Very Scandalous

I bit back I reported on the sale, not once but twice, of the Ark Encounter for $10 that, to all appearances, looked like a tax dodge gone bad.  Now Peter J. Reilly, who has written extensively about the Kent Hovind case, argues that, no it really was not that scandalous.  About the back and forth sale, he writes:
That had me a little excited, but as it turns out there is no federal tax issue. If you look at the Forms 990 filed by Answers in Genesis and Crosswater Canyon, you will find that Crosswater and AIG are both 501(c)(3) organizations and that Ark Encounter LLC is wholly owned by Crosswater making it, absent a special election, a disregarded entity. Transactions between the owner of a disregarded entity and the the disregarded entity are, for federal tax purposes, you know, disregarded. Status as a disregarded entity might not a apply for various local tax purposes. I wrote about an Orthodox Jewish school in Lakewood NJ that got tripped up by that. Apparently a similar rule applies in Kentucky, but I'm not equipped to dig deep there at this point.
Reilly sees that the coverage in the news about the transfer was very one-sided (and I did rely on that for my posts), but that there really was an ethical issue. He continues:
Ark Encounter's complaint of unfair treatment by the media might have some merit. Linda Blackford's coverage appears to me to be pretty solid and balanced, but some of what has been in the blogosphere has not been. For example, consider Dan Arel's headline - Ken Ham Sells Ark Encounter Land To Himself For $10 To Avoid Paying Taxes. I don't see that as a fair characterization as to what happened. Hemant Mehta's treatment on Patheos, though quite critical, is fairer and gives full credit to the new sources. Derek Welch of World Religion News got it backward saying that Ark Encounter sold the property to its subsidiary. The transfer was actually upstream.

On the other hand, I'm not displeased to see how they were hoist on their own petard when they transferred the property to beat the city tax. Overall the whole thing strikes me more as clumsy than smacking of deep conspiracy. All in, I think it was a mistake for the Ark to try to be frugal when it comes to supporting local services. Apparently, they think $500,000 is enough, but anything the city got over and above that would be from higher attendance.
The whole thing certainly left a bad taste in the mouths of the people of the Town, including the mayor. It also struck many, if legal, unethical. For someone like Ham, who decries the downfall of civilization because of moral failure, this seems a tad hypocritical.

Tuesday, September 19, 2017

Monday, September 18, 2017

Greek Fossil Site Vandalized

Someone has vandalized the site containing the 5.7 million year old footprints in Crete.  Australian News Limited reports:
Some four to 10 prints appear to have been hacked out of the rock.

And graffiti has been sprayed over much of the remainder.

It’s an attack with devastating implications for the science of understanding humanity’s past.

“We are fortunate that many of the best tracks remain — the people who did it clearly didn’t know what they were looking for,” Professor Bennett writes. “Our guess is that they were simply intending to sell them.”

The site had been recognised under Greek heritage laws, and local authorities were supposed to be watching it.

Greek media reports a 55-year-old man has been arrested in western Crete and that many of the prints may have been recovered.
I certainly hope so. And I certainly hope that very hefty fines and possibly jail terms will be levied against those involved. As for the people in the organization that was supposed to be watching the site, I hope they are out of a job.

Time will have to tell how much damage was actually done but this is nothing less than a travesty.  Because truly stupid people are never in short supply, many of the Neandertal sites in Europe were also looted before they could be fully excavated.  This should be embarrassing to the Greek government. 

Saturday, September 02, 2017

5.7 Million Year-Old Human Footprints Found on Greek Island of Crete

Great Googlymoogly!  This one is lighting up all over the Internet.  Fossil footprints have been found in the southern Greek Island of Crete, near the village of Trachilos, that appear to have the distinctive heel-toe-off gait of bipedal humans.  The catch? The prints are 5.7 million years old!  From PhysOrg:
Human feet have a very distinctive shape, different from all other land animals. The combination of a long sole, five short forward-pointing toes without claws, and a hallux ("big toe") that is larger than the other toes, is unique. The feet of our closest relatives, the great apes, look more like a human hand with a thumb-like hallux that sticks out to the side. The Laetoli footprints, thought to have been made by Australopithecus, are quite similar to those of modern humans except that the heel is narrower and the sole lacks a proper arch. By contrast, the 4.4 million year old Ardipithecus ramidus from Ethiopia, the oldest hominin known from reasonably complete fossils, has an ape-like foot. The researchers who described Ardipithecus argued that it is a direct ancestor of later hominins, implying that a human-like foot had not yet evolved at that time.

The new footprints, from Trachilos in western Crete, have an unmistakably human-like form. This is especially true of the toes. The big toe is similar to our own in shape, size and position; it is also associated with a distinct 'ball' on the sole, which is never present in apes. The sole of the foot is proportionately shorter than in the Laetoli prints, but it has the same general form. In short, the shape of the Trachilos prints indicates unambiguously that they belong to an early hominin, somewhat more primitive than the Laetoli trackmaker. They were made on a sandy seashore, possibly a small river delta, whereas the Laetoli tracks were made in volcanic ash.
And now, the other shoe.  How do we know how old the fossil footprints are?  
The coastal rocks at Trachilos, west of Kissamos Harbour in western Crete (Fig. 1a–c), lie within the Platanos Basin, and present a succession of shallow marine late Miocene carbonates and siliciclastics of the Roka Formation, a local development of the Vrysses Group (Freudenthal, 1969 ; van Hinsbergen and Meulenkamp, 2006; Figs. 1d, e and 3a, b). At the top, this marine succession terminates abruptly in the coarse-grained terrigenous sedimentary rocks of the Hellenikon Group (Figs. 1d and 3e, f), which formed by the desiccation of the Mediterranean Basin during the Messinian Salinity Crisis (van Hinsbergen and Meulenkamp, 2006), an event dated to approximately 5.6 Ma (Govers, 2009). The succession (Fig. 1d) contains an emergent horizon with well-preserved terrestrial trace fossils and microbially induced sedimentary structures (Fig. 3d) immediately overlying shallow water ripplemark structures (Fig. 3c).1
So, the authors are a tad more circumspect than the writers of the PhysOrg story.  The authors posit two hypotheses for their results: 1. the tracks represent the gait of a basal hominin, which explains the non-divergence and shape of the big toe as well as the shape of the ends of the other toes, which resemble those of a human foot and not a non-human foot.  This fits approximately with the dates of the north African remains of Orrorin and, perhaps, that of Sahelanthropus (although that is pretty much a surface find).

The Messinian Crisis was a period of time during the Miocene epoch during which the Mediterranean Sea almost completely dried up.  This crisis began around 6 million years ago and ended around 5.3 million years ago with what is known as the Zanclean flood.  It is estimated that once the barrier at the Strait of Gibraltar was broken, the Mediterranean Sea refilled within two years, which means that the sea level rose at an estimated 30 feet per day., lets go back here, to the story that came out about four months ago, establishing the possibility that the last common ancestor to apes and humans was in Europe.  In that study, a jaw with human root patterns and an isolated premolar that have both been attributed to Graecopithecus, were re-examined and found by the researchers to have hominin affinities, a surprising conclusion, given their age of 7.15 million years.  At the time that story appeared, I remarked that it was a bit of a stretch to hang one's hat on one premolar and partial ape-like mandible, but in the context of the new finds, maybe not so much.  This strengthens the (admittedly far-fetched) notion that our ancestors did, in fact, originate somewhere in southeast Mediterranean Europe and, over the course of the next two and half million years ago, migrated south to north Africa.

As Per Ahlberg was quoted as saying:
"This discovery challenges the established narrative of early human evolution head-on and is likely to generate a lot of debate. Whether the human origins research community will accept fossil footprints as conclusive evidence of the presence of hominins in the Miocene of Crete remains to be seen."
This is huge news.  Even if we can't place the LCA in southern Europe, we now have bipedalism extending back into the late Miocene. 

1Gerard D. Gierliński et al, Possible hominin footprints from the late Miocene (c. 5.7 Ma) of Crete?, Proceedings of the Geologists' Association (2017). DOI: 10.1016/j.pgeola.2017.07.006

Will Moroccan Schools Teach Evolution Again

Writing for the Morocco World News, Amal Ben Hadda wonders if the discovery of more early modern human remains from the site of Jebel Irhoud will prompt the government to reintroduce evolution into the curriculum:
While these new discoveries are “shaking up” the scientific community, we should ask ourselves why these theories of evolution are not being taught in Moroccan schools. Why is this scientific approach to revealing the origin of humanity not considered in the manuals programs?

From a religious perspective, some Muslim scholars support the study of human evolutionary theory. The different levels of human conception are mentioned in many verses in the Quran. However, the exegeses of these verses have been influenced by Talmudic interpretations of the Torah and have been accepted as authentic versions of the human “genesis”. As an example of this influence, there is the creation of woman from Adam’s rib. This version, interpreted from the Torah and resumed by mainstream Islamic exegeses, doesn’t exist in the Quran.

In the original text of the Torah, the chapter Genesis shows in 1:27 that man and woman were conceived at the same level and no one is superior to another. However, this woman was diabolized by the patriarchal tradition. Only the version of the creation of woman from Adam’s rib named Eve is considered by the creationists as per the interpretations of the Genesis 2:23.
It is interesting to note that Islam seems to have the same issue that Christianity does in that modern interpretations of scripture have taken hold within a large subset of Muslims regarding this issue.  In Christianity, the days of creation were never originally written as seven sequential, 24-hour periods, yet that is the perspective of a large number of conservative evangelical Christians.  He author calls for a neutral interpretation of the Koran.  I would argue that we need a similar interpretation of the Bible. 

Friday, September 01, 2017

Meanwhile, Over in South Korea...

The Korea Times is running a story about the controversy over creationism in South Korea.  Park Jae-hyuk writes:
The deep-rooted dispute over creationism has arisen here again after Park Seong-jin, the designate for SMEs and startups minister, was found to have worked for an institute supporting what most scientists regard as pseudoscience.

Creationism is a fundamentalist Christian movement that denies the theory of evolution and considers Biblical creation stories as proven facts.

Although Park told reporters this week that he “respects” the theory of evolution despite his religious beliefs, controversy over the issue will highly likely go on, given that opposition parties are expected to mention it during the upcoming confirmation hearing.

“As a Christian, I have a faith in a religion based on creation, but I do not believe creation as a science,” the minister nominee told reporters. “I’ve never individually studied creation science either.”

In response to his remarks during a symposium at Yonsei University in 2007 that “People armed with belief in creation should be deployed in every fields of society,” Park explained the remarks were just made for guests from the United States.

Saying that faith is not subject to qualification, Cheong Wa Dae has dismissed the controversy. Park quit his position as director at the Korea Association for Creation Research (KACR) just a day before his nomination.
It is not a given that this will create problems for South Korean science any more than the appointment of Betsy DeVos will in this country. That is predicated, however, on the idea that the two forms of government are broadly similar in behavior. If they are not, then things could change.Stay tuned.