why do we die?

Leo Schalkwyk schalkwy at callisto.lif.icnet.uk
Sat Oct 21 08:21:45 EST 1995


Ron Grunwald (grun at acpub.duke.edu) wrote:
: In article <DGrFr4.8D3 at uns.bris.ac.uk>, tp5145 at irix.bris.ac.uk (TJD.
: Prior) wrote:

: > As a physics student I was thinking and the question came to me Why do we
: > die, Why cant we just regenerate our selves forever. As nobody could give
: > me a satisfactory answer am asking you. If you could answer this simple!!
: > question in basic terms I would I would be most greatfull.

: No simple answer here. However, common notions run to the problem of how
: to deal with the accumulation of errors in a replicating system.

Ron Grunwald gave a good answer (mostly deleted), but there's another
point he didn't emphasise, which is that single celled organisms that re-
produce by dividing, don't senesce and die. Is there then some reason
for it which is particular to the multicellular way of life?

An important feature of that way of life is that countless cells sacrifice
themselves for the good of the whole organism. Why do they submit?  Under 
some circumstances a rogue cell could try to take 
a chance at an independent destiny by just dividing wildly. Over time
in multicellular life differences between the cells will accumulate,
and so the adherence of different cells to the common plan will also vary,
and eventually it will fall apart. In a simple multicellular organism, a
surviving cell with a suitable make up could subsequently found a new 
multicellular structure...

A mechanism for enforcing genetic uniformity in a multicellular
organism would be a limited lifespan, with regeneration of the 
whole organism from a single (germ) cell.  I think this idea goes
all the way back to Weismann.

Leo Schalkwyk



More information about the Mol-evol mailing list