24 | SCIENCE ILLUSTRATED
ASK USWhich Came First,
the Chicken or the Egg?
SHORT ANSWER:
The egg. This question is less
“philosophical” than you might
think...LONG ANSWER:
This classic scientific conundrum has
been used in a few ways, down the long
years since Charles Darwin caused all
that trouble with his “monkey book”.
Among those who dispute the reality
of evolution, it’s used to illustrate the
problem of the “first cause”. If every
animal is descended from an earlier
animal... how did the whole thing
start? That’s abiogenesis, and it doesn’t
just break the rules of how our
biosphere works right now, it breaks our
definition of life itself.Life is tricky to define. For now, we
describe life as a self-sustaining, self-
contained grouping of one or more
cells, which were generated by other,
earlier cells. From the merest bacteria
to the blue whale, all life has cells, of
one kind or another.
Also crucial to the definition is this
idea that all cells have ancestor cells,
and they go on to create new cells
themselves. Most of the time, cells just
divide into (almost) perfect copies,
either to repair damage or to increase
the total number of cells in – ie grow -
the organism of which they are part.
But every now and then, two very
special cells come together to create a
new, separate, self-contained organism
that can go off into the environmentand, in the case of the chicken, murder
penny-lizards.
This is of course the essence of sexual
reproduction. Cells combine genetic
material to create novel new forms, to
beat those fiendish cell-hijacking viruses
and all the other nasties that exploit the
way our cells work.
Repeat this process of reproduction
billions of times over millions of years,
and various copying errors, random
changes, even the occasional cosmic
ray, cause the organisms to change and,
well, evolve.
The problem of course is in
identifying when a creature stops
being a dinosaur and starts being a
bird. Evolutionary scientists
know there isn’t aTHE
BIG
QUESTION