• Question from:Oussama Atmani

Hi.. I was browsing the talk origins archive and I found this definition of biological evolution
"In the broadest sense, evolution is merely change, and so is all-pervasive; galaxies, languages, and political systems all evolve. Biological evolution ... is change in the properties of populations of organisms that transcend the lifetime of a single individual. The ontogeny of an individual is not considered evolution; individual organisms do not evolve. The changes in populations that are considered evolutionary are those that are inheritable via the genetic material from one generation to the next. Biological evolution may be slight or substantial; it embraces everything from slight changes in the proportion of different alleles within a population (such as those determining blood types) to the successive alterations that led from the earliest protoorganism to snails, bees, giraffes, and dandelions."

Douglas J. Futuyma inEvolutionary Biology, Sinauer Associates 1986

It doesn't take in consideration epigenetic evolution is that because it's relatively old and does that make it inaccurate
Thanks in advance.

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  • University of Bristol
  • Posts: 4,230

great question and yes I'd say it is still a comprehensive and up to date definition (as well as being beautifully written).

focusing on:
Biological evolution ... is change in the properties of populations of organisms that transcend the lifetime of a single individual.

don't forget that epigenetics only affects gene expression in an individual and not a whole population. there are thought to be cases where an epigenetic change can be transgenerationally inherited but that is still work in progress. see
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2989988/

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  • University of Exeter
  • Posts: 1,011

Somewhat controversially I would add that  - in my view - the importance of epigenenetics as distinct from genetics is also overstated at the moment.

By this I don't mean that "epigenetic" mechanisms aren't important, but rather that an referring to DNA sequence changes as genetic and all other parts of inheritance as epigenetic rather misses the point that genetics as a field existed long before we knew the struture of DNA (let alone were able to sequence it). So in part the increasing prominance of "epigenetics" stems from (some) people narrowing the definition of "genetics" - which is fine in principle but is leading to some "wheel reinvention" as people discover "new evidence for epigenetic inheritance" that we've known about for a long time!

Sorry - personal gripe! I like Futuyma's definition too.