[Rockhounds] Fossils key to fulfilling Darwin's 160-year-old prediction

[Tim Fisher]

We all miss Stephen Jay Gould, his punctuated equilibrium paper was genius.
I also think it's more environmentally driven than the "species wars". And I
also think it can and should be used to describe climate change, as the
planet flips rapidly from one state of equilibrium to another. Sloooowly
paleontologists and geologists are realizing that the major climate changes
(that mostly resulted in extinction events and thus more openings for rapid
speciation) didn't happen over centuries. The Paleocene-Eocene change that
I'm most familiar with has gone from millennia to centuries to perhaps
decades with ongoing research. And a few more recent, like the
Pliocene-Pleistocene event are being compared to the current event, and it's
thought that they were also very rapid.

Tim Fisher
Orerockon.com
Email nospam at orerockon.com


-----Original Message-----
From: Rockhounds [mailto:rockhounds-bounces at rockhounds.drizzle.com] On
Behalf Of Alan Silverstein
Sent: Tuesday, December 18, 2018 1:24 PM
To: rockhounds at rockhounds.drizzle.com
Subject: Re: [Rockhounds] Fossils key to fulfilling Darwin's 160-year-old
prediction

> Fossils key to fulfilling Darwin's 160-year-old prediction December 
> 12, 2018, University of Salford 
> https://phys.org/news/2018-12-fossils-key-fulfilling-darwin-year-old.h
> tml

Brief and interesting, thanks.  It reminds me, though, of some "mind
blowing" (at least to me) new perspectives I got a while ago, probably from
Dawkins' book, "The Greatest Show on Earth".

Quibbles continue over definitions of today's species.  It's not as simple
as we might have learned in middle school, "successful interbreeding," given
microbial direct DNA exchanges, and varieties/subspecies, etc.  Even if
you're up to speed on all that, it's still easy to forget that:

- Species morph over time, and not necessarily smoothly.  Consider
  "punctuated equilibrium."

- In almost every case, parents at least theoretically should be able to
  interbreed with their direct offspring!  So when is a new species
  created?  Never suddenly, only after many generations of physical or
  virtual separation and mutation/evolution.

  (It still bugs me how can chromosome count ever change, since it
  cannot happen all at once, but it's a small integral number, and
  mismatches interferes with sexual reproduction.)

- And yet, it should always (except in case of direct DNA exchange) be
  at least theoretically possible to trace members of different species,
  even wildly diverse ones (like cantalopes and chinchillas) to "last
  common ancestors", meaning common parents, of siblings that forked
  forever (for whatever reason) without interbreeding (neither directly
  nor in later generations).

- So, back to fossils:  Nowadays I'm amused by debates over how to
  categorize their species, especially considering that in most cases we
  only have age, locale, and (some) anatomy to go on, but no DNA.
  Definitions of species can be relatively fuzzy, even at a GIVEN time,
  and the tree of life is a tangled mess over the long run.

Cheers,
Alan Silverstein

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