Ancient Jawbone Could Shake Up Fossil Record

Not everything in life works out as we might hope – for instance, the crowds lining the route of today’s Stage 7 in the Tour de France were hoping for a French stage winner to coincide with Bastille Day, but in the end it was German rider Linus Gerdemann of the T-Mobile team who powered away from the chasing peloton to win the stage, taking over both the white jersey (best young rider) and yellow jersey (overall race leader) in one prolonged burst of exceptional riding through this gruelling day, that gave him his first stage win since the Tour de Suisse in 2005 – in other words a great result for him and his team, but not the one the partisan crowds were hoping for, even though they sportingly cheered the winner of this first mountain stage to the echo, as he sped past them.

“As in professional cycling, so in palaeoanthropology”, is probably a saying unattributable to anyone ever, but the point I want to make is that despite the hype predicting the discovery of a missing link in hominid evolution, I’d be surprised if that was the result, although we might instead discover more unexpected details from the fossils, which in the end might be just as valuable as a putative missing link.

National Geographic have more on the recent finds from Woranso-Mille in the Afar region of Ethiopia, not a million miles for where Kambiz is at this moment, and although there are no new developments to report, this picture of a complete mandible warrants a quick post in its own right. First, an excerpt from the linked article …

Though more research needs to be done, the group says the bones could bridge the gap between two known human ancestor species.

Australopithecus anamensis lived some 4.2 million to 3.9 million years ago, and Australopithecus afarensis—the species to which Lucy belonged—thrived from 3.6 million to 3 million years ago. (Explore our human roots through the Genographic Project.)

Some researchers believe that Lucy and others of her species were descendants of A. anamensis—and these new Ethiopian jawbones could end that speculation. (See map of Ethiopia.)

Many tend to be quite wary of finds that are touted as being able to fill in this or that missing gap, especially from times as far back as these, when there was a veritable myriad of hominids and associated others patrolling the landscapes, many of whom we are probably still unaware.

Reading through other very old finds, the tendency seems to be for many for these types of fossils to show traces of different lineages all mixed in together, and I wouldn’t be surprised if the analysis of the Woranso-Mille fossils presents a similar array of features – my point being is that there were all sorts of archaic others sharing the same living space, and in my opinion, hybridisation was a big factor back then, and moreover, emphasis should placed on explaining that right up until the about 25,000 bp there were at least two or three types of hominids around, and that we moderns are the only species ever to have lived in the absence of others.

Mention is sometimes made that there is a perceived over-enthusiasm for designating each new specimen find as a species in its own right, and while such general classifications may help in referring to this or that specimen from a particular site at a particular date, the lines between some of the named species can become very blurred.

“People are prepared to accept that there’s diversity,” said Chris Stringer, a research leader at London’s Natural History Museum, who was not involved in the latest work. “But of course what is uncertain is how widespread it was through the last six million years.”

“If we had a complete fossil record, would we see branching events right through that period of time … or were there only specific times of branching events?” Stringer said.

As we’ll never have a complete fossil record, questions such as these may never be fully resolved – however it is thanks to the work of Yohannes Haile-Selassie and many others in the field, that we have even the faintest glimmering of which hominids and associated fauna were gracing the Earth over the past few million years.

Three years of research in the area where the latest bones were found have yielded more than 1,900 vertebrate specimens. They include human ancestor species from many time periods, as well as other animals such as mice, elephants, monkeys, rhinoceros, primitive horses, and fish.

A partial skeleton of a human ancestor was discovered in 2005, and Haile-Selassie’s team continue to excavate what’s left of it. Haile-Selassie said his team would need some time to study the bones and come up with conclusions about the relationship between A. anamensis and A. afarensis.

“Two years down the line we may be able to say something about it,” Haile-Selassie said. “Patience is needed.”

The point here is that although there have been many spectacular finds over the years, it’s maybe worth viewing them as stage victories in a very long event, which has still a great distance to run, rather than try to attach too much importance to one single find, or win. Just as Linus Gerdemann had a great victory today, tomorrow morning he and the other 180-odd Tour riders have to get back in the saddle, and do it all over again – indeed, tomorrow’s Stage 8 will be even harder than today, and they still have another two weeks’ cycling before that final stage at the Champs-d’Elysee on July 29th. Good luck to all concerned in both ventures, would be my closing words. (TJ)

see also: Hominin Dental Anthropology – ‘Some More Old Teeth

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