

Jaw bone discovered in Ethiopia is oldest known human lineage remains - diodorus
http://www.theguardian.com/science/2015/mar/04/jaw-bone-discovery-in-ethiopia-is-oldest-ever-human-lineage-remains

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tjradcliffe
It's worth remembering in these cases that the date of the earliest fossil
find is only weakly related to the date of the earliest instance of the
fossilized species:
[http://www.tjradcliffe.com/?p=1610](http://www.tjradcliffe.com/?p=1610)

Sparsely sampled distributions will necessarily have tails that are not
represented in the sampled data, and for early humans those tails could
plausibly go back much, much further than the current record shows.

As such, we can expect that there will be a slow, steady stream of
"surprising" early finds that push back hominid evolution to much longer ago
than previously appreciated. The same is true of dinosaurs or any other
species: the rarity of fossilization events is such that the probability of
the earliest surviving fossil being particularly close to the emergence of the
species is just not that high.

It would be interesting to do a serious analysis of the fossil discovery
distribution to see if we can make a better estimate of the earliest emergence
of hominids based on empirical estimates of fossilization and discovery
probabilities.

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sunwooz
How do you define an emergence of a species when these hominids are always in
a state of constant change? Wouldn't this mean that there is no concrete way
to determine if a fossil is from 'one side' or the 'beginning'(earliest point)
of a species?

Might be slightly off-topic.

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jonchang
Well, this is an open question in evolutionary biology :)

One important thing to keep in mind is that species are hypotheses that can be
tested, and the interpretations can vary from person to person and field to
field. For example, many molecular geneticists will often discover new cryptic
species on the basis of their DNA sequences, that a morphologist might not
consider to be a true species. For fossils, of course, there almost always
only morphological evidence for species.

The relative roles of anagenesis (change within a species) and cladogenesis
(splitting event that creates two new species) in evolution is still being
investigated, especially by paleontologists. One of many problems is that the
fossil record is extremely incomplete, and so it's difficult to determine
whether anagenesis or cladogenesis dominates. For me (as a non-paleontologist)
my simplifying assumption about evolution is that anagenetic change doesn't
occur, but again this is still an area of active research.

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spodek
> Jaw bone fossil discovered in Ethiopia is oldest known human lineage remains

Trilobite fossils are older human lineage remains, or at least plenty of
species we know led to mammals, if trilobites didn't descend to us.

The article specifies "... that belong to the genus Homo, the lineage that
ultimately led to modern humans," which is probably what the headline meant.

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camillomiller
The fact that I read the title and immediately thought of a silly and mistyped
headline for a piece about a wearable device means I should be reading less
about technology.

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robmcm
As I read the title I started thinking, what's "news" about Ethiopians having
Jawbone Ups...

