New Scientist recently managed to write an article discussing the date for the human-chimp split, omitting one of the most decisive pieces of evidence, to drag the field back 10 years.
The claim was made that the split might be at or before 8 million years ago, earlier than scientists had been thinking.
Why this new claim? Because of new thoughts about the speed of the genetic clock. New Scientist tells us of recent works that suggests the rate of genetic change from one generation to the next, measured in people and chimps alive today, is a lot slower than we used to think.
This would put the vital benchmark date of our split from orangutangs under suspicion; however that is no more under suspicion than the new estimate for the genetic clock, especially over long range. It is known that it is not a straightforward job to try to estimate the long-range rate of genetic change by looking at what appears to be the short range rate (see refs below: Verginelli et al. 2005; Ho et al. 2005; Emerson 2007). It would be rash to take this recently suggested clock rate at face value, nail it to the wall, and then force all our other estimates to suit it, the way New Scientist has done.
Especially not in the way they started rethinking the orang split. It had been estimated at up to 20mys. Now we are told that must be wrong by a factor of two. Unfortunately an orang split of 40mys would be immediately recognised by everyone as absolutely impossible. Even 30mys (see below) is unbelivable.
What fossils throw light on the early apes? The first evidence of tail-less primates near our lineage, is of the proconsuloids, which first appeared 23mys ago. The Proconsul genus lasted till maybe 17mya (proconsuloids survived even later), and their novelty was possibly in preferring to hang beneath branches by both hands and feet, more so than their tailed forebears. They differed from those ancestors in preferring a naturally stable equilibrium, avoiding the need for the balance-assisting tail; they differed from the more advanced apes that followed them, in not yet relying on just the arms: proconsuloids’ shoulders were not optimised for two-armed brachiation.
Orangutangs’ shoulders are not like proconsuloids. Instead, a new form of ape, exemplified by Morotopithecus, appeared at some time between 20.6 and 14.3 million years ago, which was much more like modern apes, or at least like modern asian apes. Just to take a moment to knock the bizarre newly suggested split date for orangs on the head at this point, a figure even of 30mys would imply two evolutions of not just tail loss due to quadrupedal hanging under branches, but then also of the shift to two-armed brachiation… and all without any fossils to suggest either the double evolution or an early date.
Now we look to the decisive piece of evidence mentioned at the start [also click on Filler ref below], and supplied to us courtesy of spinal surgeon Aaron Filler. Morotopithecus, now centre-stage, is maybe 20mys old and has an unusual spine: a human spine! Our spinal column is relatively deep under the surface, so that more superficial muscles along our back can work efficiently to keep us upright. This applies particularly when we’re standing upright, rather than hanging upright under a branch by two arms, because when we’re hanging, gravity straightens our trunks automatically. You’d expect our back to be different from chimps’ and gorillas’, but you wouldn’t expect what we see: their backs are completely unlike Morotopithecus’. Worse, chimps’ and gorillas’ backs are so different from each other that they solve the support of their diagonal back configuration differently! Gorillas interlock the vertebrae whereas chimps suspend from the pelvis.
This pattern of similarities and differences in spinal design means one thing: we were some kind of upright when Morotipithecus was around maybe 20mya, and chimps and gorillas dropped down onto all-fours independently.
This solution has been continuously checked against all the evidence ever since it was put forward decades ago, and explains everything much better than any other theory. Indeed, sensible people were believing this pattern of stance evolution even before being shown the spinal evidence! (Full details and extensive further refs in The Secret Dinobird Story.)
Here are the final pathetic twists to the new idea New Scientist is trying to sell you:
1: We can’t be told that upright-since-Morotopithecus is the best theory because too many people in the field aren’t happy with the idea (though we don’t know why because they never even mention it).
2: We can’t even ever be told of the existence of the upright-since-Morotopithecus theory because too many people in the field aren’t happy with the idea.
3: Those folks whose opinion is so precious that we’re not allowed to hear alternatives are not experts in spinal surgery, but workers in museums. Their knowledge of spines is not tested every week of the year with clear medical outcomes and under the threat of multi-million pound lawsuits – it’s never tested in any material way at all.
4: Here’s the most absurd thing: the driving reason behind their wish to grab but distort any new finding to support an early split between chimps and apes is… the existence of probably upright fossils of around 6mya! They can’t get their mind round even the possibility of an upright chimp ancestry long enough to realise that it means upright fossils 6mya do not imply a pre-6mys split!
[These early-split plonkers are as influential as they are stupid. It’s pretty clear to anyone studying the odd behaviour of scientists such as palaeontologists over any length of time, that the major driving force they follow is not working out the science for themselves but avoiding being seen as someone with odd ideas. Seriously. It’s really only that that counts; any other consideration is a minor influence. Paradoxically, this lilly-livered pack-attitude is precisely what causes daft ideas to thrive more than anything else. Even the once-great John Hawks has had his reliability down-graded by advising people not to risk looking like a… well kook is the name he uses. He even suggests that merely drawing attention to the standard groupthink processes that corrupt palaeo is ill-advised because… it makes YOU sound like a kook! No John, we don’t point out that all new theories were lambasted at the start, to justify our theories – we do it to UNjustfy the criticisms. Don’t try and pretend we’re stupid enough to confuse them, even if you are yourself! Moronic kneeejerk attacks on anything you can’t be bothered to understand, really is the major issue in palaeontology.]
And we haven’t even brought Ardipithecus into the picture. The full picture of the line to upright humans/chimps at the time of the split was filled in when Ardipithicus ramidus ramidus was revealed in Oct 2009… but those revealing it were White and Lovejoy – two of the main persistent ignorers of the upright chimp ancestor theory! (And check out another posting highlighting bad palaeo science.) If Russia could be described as a riddle, wrapped in a mystery, inside an enigma, then the current practice of palaeoanthropologists could be characterised as a joke factory inside a one-legged arse-kicking competition inside a lunatic asylum. In the BBC’s recent three-part series on human evolution, the three excellently preserved crucial fossils were a neanderthal, the Nariokotome boy (H. erectus), and Lucy and the other little A.a., both Australipithecus afarensis. A fourth one should have been the crucial but embarassingly controversial Ardi. But we can’t let the public know that science is all about duelling theories, now can we! In those programmes, the real current best human-chimp split date of 4mys was never mentioned. Interestingly, Hawks was included in those programmes as well as being quoted in the New Scientist article. By the time of the latter he’d finally flipped into la-la “never-contradict-the-Natural-History-Museums-land”. He seems to have abandoned his well-advised 4mys split date he’d worked out himself from true expert analysis of DNA experiments: “I think this will affect pretty much every event in human evolution, from the intial divergence of our lineage to the dispersal out of Africa”. Odd though that he doesn’t seem to have blogged on this ‘new compelete shakeup’.
The final list of errors represented by the latest New Scientist piece includes:
* Don’t gather ALL the possible theories and eliminate the ones that fail to explain, like you’re supposed to;
* Only consider some evidence; never ever mention other evidence inconvenient to people we daren’t contradict; airbrush its originators as “kooks”. (Alternatively, you may use the word “cranks”)
* Never ever do anything, even good science, that might make you come up with or adopt a new theory, for fear of looking like a member of a minority. Do keep in training with the eye-rolling, face pulling and snide comments to point out kooks you’ve discovered.
* But you can keep taking a salary as a responsible scientist, science journalist, or science journal editor, no matter how crap the ideas you foist on the public.
So be aware that, judged by what they recommend, few of the people you rely on for good professional science advice in this area are actually sound scientists. They’re out by at least a factor of 100%.
Emerson, B.C. (2007) Alarm Bells for the Molecular Clock? No Support for Ho et al.’s Model of Time-Dependent Molecular Rate Estimates. Syst. Biol. 56(2), 337-345.
Filler, A. (2007) Homeotic evolution in the Mammalia: diversification of Therian axial seriation and the morphogenetic basis of human origins. PLoS ONE 2, (10), e1019. doi:10.1371/journal.pone.0001019.
Ho, S. Y. W., Phillips, M. J.,Cooper, A. and Drummond, A. J. (2005) Time dependency of molecular rate estimates and systematic overestimation of recent divergence times. Mol. Biol. Evol. 22, 1561-1568.
Verginelli, F., Capelli, C., Coia, V., Musiani, M., Falchetti, L., Ottini, L., Palmirotta, R., Tagliacozzo, A., De Grossi Mazzorin, I. and Mariani-Costantini, R. (2005) Mitochondrial DNA from Prehistoric Canids Highlights Relationships Between Dogs and South-East European Wolves. Mol. Biol. Evol. 22(12), 2541–2551.