Friday, 5 December 2008

Debunking Corner - Homo floresiensis - Hobbits

I'm sure everybody watched the Alien From Earth if not follow the link. Especially because I am about to lay some serious stupid on you. I was randomly surfing the web and stumbled across two articles on Homo floresiensis both of which were written by creationists.

The first, called The Hobbit File is pretty straightforward. H. floresiensis was compared, and found to be similar to australopithecines and since australopithicine means "southern ape" H. floresiensis is an ape. They discount the microcephaly argument:
The "microcephalic dwarf" interpretation would only work if there was a double deformity, i.e.
dwarfism plus microcephaly - they are not the same. Dwarfs have normal brain sizes even though their bodies are small. This means they have big heads in proportion to their bodies. Microcephalics with brains as small as H. floresiensis are severely mentally retarded and unlikely to survive in primitive conditions, unless they are cared for by normal humans.

Which is about as good as their argument gets...
The second The Flores Skeleton and Human Bariminology is somewhat more interesting, although equally confused.

Wise argues that because Homo erectus is found on three continents they represent the post-Babel diffusion of humans (like a lot of creationists he considers H. erectus to be human) and, therefore, the Lower and Upper Pleistocene were post-Babel as well. So the radiocarbon date of 18,000 BP is totally consistent with a post-Babel time frame.

Wise then turns to the question of whether the Flores remains are human and cites the tools and charred animal remains as indicating that the remains are human. In looking at the morphology of H. floresiensis Wise cites the morphology linking it to H. erectus:

The fact that the Flores skeleton post-dates H. erectus and contains characters similar to unique erectine morphologies of Indonesia (e.g. the double mental foramina in the mandible: Brown, et al. 2004, p. 1058) suggests the Flores skeleton might be a descendant of H. erectus. Since Homo erectus is considered human by a number of creationists (e.g. Lubenow 1992, 2004; Wise 2002, p. 238; Wieland 2004), it is most likely that the Flores skeleton is human.This is where things start to get interesting. Wise turns next to a consideration of human variation. He notes the small stature and small brains size and attributes it to a cessation of brain growth far earlier than in any known human (or H. erectus for that matter). For Wise this means that there are four distinct human morphologies represented by H. erectus, Neanderthals, H. floresiensis, and modern human. Wise then makes a confusing argument about how the decreasing age of attainment of sexual maturity indicates that lifespan is decreasing (even though it's not) and argues that humans have experienced heterochrony in developmental rates. Having just argued that human lifespan was decreasing Wise then argues that:

Even though each of these involve increased growth rates in the past (rather than the decreased growth rates over the longer time range, as suggested by the biblical account), these studies and others do evidence heterochrony in human history (see also Minugh-Purvis and McNamara 2002), something which is evidenced in both biblical and historical data. The unique developmental program of Homo floriensis would represent yet another example of heterochrony in human historyIn other words, even though the arguments he just made were bullshit, Wise is still correct 'cause, hey, heterochrony happens. Wise argues that the distinct morphologies represented by H. floresiensis and Neanderthals probably arose due to genetic drift in small geographically isolated populations. The Bible says humans went through a bottleneck:

The Bible indicates that all humans are derived from a man and a woman who lived less than 10,000 years ago. Then, less than two millennia later (at the time of the Flood) the human population went through a population bottleneck of 8 people. Although the calculations have not been re-evaluated by creationists, these facts are probably consistent with the diversity of modern human mitochondrial DNA being derived very recently from one woman (Cann et al. 1987; Gibbons, 1993) and modern human Y-chromosome DNA being derived very recently from one man (Dorit, et al. 1995).Three things need to be said about this. First, from Cann et al:

All these mitochondrial DNAs stem from one woman who is postulated to have lived about 200,000 years ago [bolding mine- afarensis}, probably in Africa.Second from Dorit et al:

A coalescence model predicts an expected time to a most recent common ancestral male lineage of 270,000 years (95 percent confidence limits: 0 to 800,000 years[bolding mine- afarensis]).That doesn't sound very recent to me...(heh, he got the title to the Dorit et al paper wrong too).

Third, the fact that a given gene coalesces at a given time does not mean that that individual was the only person alive at that time.

Wise then goes on to make a confusing argument about the multiregional continuity argument and convergent evolution on the human form - something he chalks up to ontogenetic redundancy. Later he says that these changes happened post-Babel and then the respective distinct populations migrated to areas where they felt the most comfortable due to their morphology. Basically, the morphologically similar erectus morphology diverged into several distinct morphologies which then converged on the human morphology.

Then Wise gives the farm away:

Various creationist arguments and studies (e.g. Jones 1972; Wood and Murray 2003, pp. 71-2; Wood 2005) suggest that the created kind may be roughly approximated by the taxonomic level of the family.A created kind is the equivalent of the "family" in taxonomy? Really? That means that all this is a created kind:

* Primates (Order)
* Haplorrhini (Suborder)
* Simiiformes (Infraorder) [apes and monkeys]
* Catarrhini (Parvorder)
* Hominoidea (Superfamily) [apes]

Proconsul africanus

* Hominidae (Family) [great apes]
* Homininae (Subfamily) [includes gorillas but not orangutans]

Pierolapithecus catalaunicus

* Hominini (Tribe) [includes chimpanzees but not gorillas]

Sahelanthropus tchadensis, common ancestor with chimpanzees[citation needed]
Orrorin tugenensis, first species after split with chimpanzees[citation needed]

* Hominina (Subtribe) [humans are the only surviving species]

Australopithecines: includes Paranthropus and Australopithecus


* Homo (Genus)

Homo habilis
Homo ergaster
Homo erectus
Homo heidelbergensis

* Homo sapiens (Species)

Homo sapiens idaltu

* Homo sapiens sapiens (Subspecies)

Yup, orangs, chimps, gorillas, australopithicines, and humans are all the same "kind"!

It's all downhill from there, but you can read it for yourself...

From Afarenis.

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