Primary events in the history of life

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Martin - 08 Jun 2006 03:11 GMT

Greetings folks. This is my first time here. I'd like to get a little
feedback on something. I need to identify the ten (or so) primary
events in the history of life. The list that I've come up with is:

Hominids
Flowering plants
Vertebrates
Land life
Multicellularity (animals, plants, fungi)
Complex phytoplankton (sex)
Eukaryotic cell (cell nucleus)
Oxygenic cyanobacteria (oxygen atmosphere, primitive ecosystems)
Protocell (Prokaryotes)
Organic molecules

Any suggestions on what to add or subtract?

This is pretty important to me. Aside from soliciting casual comments,
I would be willing to pay a consulting fee to get a more careful
answer. This wouldn't be a big job, maybe a few hours. (I'm assuming
some of us here have PhD's.)

Thanks,

Martin

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bae@cs.toronto.no-uce.edu - 09 Jun 2006 02:52 GMT

>Greetings folks. This is my first time here. I'd like to get a little
>feedback on something. I need to identify the ten (or so) primary
[quoted text clipped - 12 lines]
>
>Any suggestions on what to add or subtract?

Kind of anthropocentric, don't you think? If we were clams, we'd find
your top four levels unimportant. If we were beetles, of which there
are gazillions of species, an incredibly successful taxon, the top
three levels would be meaningless. Bacteria, and Archaea, which are
truly omnipresent, from the top of the atmosphere to kilometers below
the surface, and in locations where nothing else can survive, might
figure it all went downhill with the eukaryotes, or even with
chlorophyll.

Victorian science had a concept of The Great Chain of Being, with all
life arranged in an ascending ladder with Homo sapiens at the top, the
culmination of evolution. While powerfully appealing, it's hardly
objective.

>This is pretty important to me. Aside from soliciting casual comments,
>I would be willing to pay a consulting fee to get a more careful
>answer. This wouldn't be a big job, maybe a few hours. (I'm assuming
>some of us here have PhD's.)

I'd leave hominids off the top. An argument for vertebrates is that
all large land animals and most large marine species are vertebrates.
While flowering plants are prominent features of most modern land
ecosystems, there were quite elaborate ecosystems long before they
arose.

I think you'll have to define exactly what you mean by "primary event".
It would help if we knew the purpose of your list.

I could make some comments about the terminology and how to divide up
the lower levels of your scheme, but I'll leave that to some of the
actual Ph.Ds here.

I hope these casual comments help.

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Martin - 09 Jun 2006 03:54 GMT

> Kind of anthropocentric, don't you think? If we were clams, we'd find
> your top four levels unimportant. If we were beetles, of which there
[quoted text clipped - 29 lines]
>
> I hope these casual comments help.

It's a start, and thanks. Yes, I do see the possibility of bias, and
the first thing I need is some rule or rules on how to make such a
list in an objective way. I've been thinking about this, but I haven't
come up with much. The list I presented is taken from a book entitled
"Major Events in the History of Life." It's authors are a stellar bunch
(J. William Schopf and Stanley Miller, among others).

I'm preparing a web site that will present basic science concepts. Part
of it involves a time line showing the major events from the big bang
on. (And BTW, I didn't mean to suggest that I have a PhD. I just meant
that if I were to hire a consultant, I would want that person to be
qualified.)

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Bob - 09 Jun 2006 05:47 GMT

>It's a start, and thanks. Yes, I do see the possibility of bias, and
>the first thing I need is some rule or rules on how to make such a
>list in an objective way. I've been thinking about this, but I haven't
>come up with much. The list I presented is taken from a book entitled
>"Major Events in the History of Life." It's authors are a stellar bunch
>(J. William Schopf and Stanley Miller, among others).

I had somewhat the same reaction to your initial post.

Now you have given some context.

Seems like you just choose some milestones that you find interesting,
scattered along the timescale at useful points. (Are you using a
logarithmic time scale?) There is nothing objective about it. They
need to be appropriate to you and your intended audience.

Are you going to "explain" each item you list? If so, they become part
of a story that you choose to put together. As you develop the story,
you may find you want to adjust the points you make, to make the story
better.

Do you want to include things like mass extinctions? Or the
human-based processes of domestication, and now genetic engineering?
Or ancient continents? Depends on your goals and audience.

If you want to use someone else's list, be sure to give the date they
proposed it. Ideas from 1975 and from 2000 will differ. (You could
probably have a lot of fun comparing such lists from over the
centuries!)

Try to get the language right. Your post talks about events, but your
list is of things, not events.

bob

>I'm preparing a web site that will present basic science concepts. Part
>of it involves a time line showing the major events from the big bang
>on. (And BTW, I didn't mean to suggest that I have a PhD. I just meant
>that if I were to hire a consultant, I would want that person to be
>qualified.)

Reply to this Message

Martin - 09 Jun 2006 17:30 GMT

Bob,

Thanks for the feedback.

> I had somewhat the same reaction to your initial post.
>
[quoted text clipped - 3 lines]
> scattered along the timescale at useful points. (Are you using a
> logarithmic time scale?)

Actually, this timeline covers major events from the big bang onward.
The simple logarithmic scale used in astrophysics is unusable if you
want to include life and social science events. All these later events
become bunched up at the top. The logarithmic scale has to be modified.

>There is nothing objective about it. They
> need to be appropriate to you and your intended audience.

Are you saying that you feel that there is no way to do this
objectively?

> Are you going to "explain" each item you list? If so, they become part
> of a story that you choose to put together. As you develop the story,
> you may find you want to adjust the points you make, to make the story
> better.

Yes, I plan to include some explanation, and I have seen the need to
make adjustments.

> Do you want to include things like mass extinctions? Or the
> human-based processes of domestication, and now genetic engineering?
[quoted text clipped - 4 lines]
> probably have a lot of fun comparing such lists from over the
> centuries!)

Yes, I know that old literature would present problems. The book I
mentioned has a publication date of 1992. This is an important part of
why I am casting about for alternate points of view.

> Try to get the language right. Your post talks about events, but your
> list is of things, not events.

Yes, again. I'm trying to use a list of phenomena: elementary particles
... galaxies ... prokaryotic cell ... multicellular organisms ...
hominids ... language ... I am using the word "event" to refer to the
emergence of phenomena.

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Bob - 12 Jun 2006 03:14 GMT

>> Seems like you just choose some milestones that you find interesting,
>> scattered along the timescale at useful points. (Are you using a
>> logarithmic time scale?)
>
>Actually, this timeline covers major events from the big bang onward.

The most recent big bang, I presume. :-)

>The simple logarithmic scale used in astrophysics is unusable if you
>want to include life and social science events. All these later events
>become bunched up at the top. The logarithmic scale has to be modified.

Actually, I was thinking logarithmically the other way -- so that you
have more space for more recent events. (i.e., years before now)

But this is not a right/wrong point; a log scale simply allows you an
option. I would guess, though, that the density of events increases as
you go on, but of course that will depend on your choice of events.
You may have one main line, plus expanded regions.

>>There is nothing objective about it. They
>> need to be appropriate to you and your intended audience.
>
>Are you saying that you feel that there is no way to do this
>objectively?

Sort of.

I think my main point is to distinguish "important" and "interesting".
Both are value judgments, in a sense. But you don't need to justify
"interesting" to anyone else. If you think it is interesting, both now
and after you have written your story about it, then it is
interesting.

If the purpose of your site is to promote interest in science to a
general audience, then writing about what interests you is a great way
to go, at least to get started.

The problem with "important" is that it carries some air of authority
-- even if we know relatively little, or have considerable difference
of opinion. A good example would be origin of life. Sounds important
(and of course if everyone agrees it is obviously important, then
getting authority for it is not an issue). But we have no idea when or
how it occurred. (Perhaps we have an idea when, but some suggest that
life , or at least organic molecules, came to earth from space. If so,
then we have no idea when it happened.) Presumably "interesting" --
enough so you want to include it. And you may want to discuss some
ideas about it. It is actually a good lesson at a general science site
to learn that science is uncertain about things -- even if some in the
field have strongly held opinions.

As another example... you suggest that emergence of land animals is
noteworthy. ok. Perhaps would also want to note the whales going back
to sea. I wouldn't argue "importance", but I might argue "interest".
(I don't care which way you come out on this point, or any of the
others, so long as you see the point of raising the question.)

You might even argue that the birthdates of your parents were
important -- certainly important in you getting this site up. But you
would probably get little support for that from the authorities.
"Important" can depend on your vantage point.

Don't be overly influenced by PhDs (including mine). We can all
contribute to the discussion, but some PhDs are fairly narrow in their
view, some very broad. Some are such strong advocates for a particular
view in a developing area that they may lose sight of the overall
picture.

If you main goal is a broad view of science for the general audience,
keep that goal at the forefront. Tell a good story that is
scientifically sound, even if simplified and incomplete.

Think of it this way... If there were an objective list of historical
events, it would be written somewhere -- and you wouldnt need to
write it.

bob

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Natural Science Forum / Biology / Biology / June 2006

Primary events in the history of life