[Taxacom] Phylogenetic divergence dating

John Grehan calabar.john at gmail.com
Thu Jun 8 09:22:41 CDT 2017


Naturally the age of a taxon depends on how fossils are interpreted. If
older fossils are regarded as conspecific with H. sapiens then the minimum
age will be even older. If heidelbergensis were regarded as just a
variant of modern humans then that pushes the species perhaps to at least
1.3 Ma. Many evolutionary biologists imagine a center of origin for the
origin of taxa, and the location of the oldest fossil is a frequent
criterion (even though this has no scientific basis), although the most
frequent criterion used these days is that the center of origin is the
region if not actual location of the smallest group separated from the rest
by the most basal internal node (again this has no scientific basis).

John Grehan

On Wed, Jun 7, 2017 at 10:43 PM, Kenneth Kinman <kinman at hotmail.com> wrote:

> Well,
>
>        I include Homo sapiens heidelbergensis in Homo sapiens, and it
> goes back to about 600,000 to 700,000 years ago.  And it is known from
> Spain, so specimens in Morocco 300,000 years ago  would be no surprise at
> all.
>
>
>        As for an East African center of origin, that is only valid if one
> excludes heidelbergensis from Homo sapiens.  Did they compare these
> specimens to heidelbergensis?
>
>
> ------------------------------
> *From:* Taxacom <taxacom-bounces at mailman.nhm.ku.edu> on behalf of John
> Grehan <calabar.john at gmail.com>
> *Sent:* Wednesday, June 7, 2017 9:14 PM
> *To:* taxacom
> *Subject:* [Taxacom] Phylogenetic divergence dating
>
> Just an interesting recent claim for fossil Homo sapiens at 300,000 years,
> 100,000 older than the previous oldest fossil
>
> "The newfound Homo sapiens fossils — three young adults, one adolescent and
> a child of 7 or 8 — date back roughly 300,000 years, says a study in this
> week’s *Nature*. The next-oldest fossils of Homo sapiens, the scientific
> name for humans, are about 200,000 years old."
>
> Just makes the point that the oldest fossil is only the oldest fossil and
> therefore the minimum age of a taxon, as is any molecular extrapolation no
> matter how many molecular systematists continue to misrepresent their
> divergence estimates.
>
> The 300,000 year old fossils are from Morocco, which does not fit well with
> the East Africa center of origin model - although no doubt someone later
> will say that the Moroccan fossils are not really H. sapiens.
>
> John Grehan
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