I have heard that Richard Dawkins popularized this view in his 1976 book The Selfish Gene, though I know that it is in no way his own invention. Nevertheless, I must ask: how could any view of evolution not be gene-centric? Genes are what is passed on in reproduction, and evolution involves the passing on of fitness-producing genetic traits. So how could any theory of evolution not be described as “gene-centric” and not revolve around the passage of genes?
While the Gene-centric view is widespread now, there was earlier in in the 20th century a large field of proponents for what was called the Jennifer-centric view.
Sorry, that is perhaps the lamest comment Ive ever made, but I somehow couldn’t get myself to delete it.
Anyway, the view of group-selection is often in opposition to the gene-centric view. For instance, people have suggested that groups of animals do certain things in order to achieve some sort of advantage for the group, such as population control. It has been claimed that the warning chirp of some birds couldnt have been for their own sake. Etc. Personally, I agree with your viewpoint that gene-centrism is the only thing that makes sense.
Evolution has been sometimes described on working on the level of individual organisms. For example, one organism may be more fit for a particular environment than another. (Or, as mr. jp points out, even on the level of groups of individuals.)
Dawkin’s point was that the fitness of a particular individual isn’t really important, what’s important is the fitness of the genes themselves. And that in some circumstances an individual may act to his own personal detriment in order to benefit copies of his genes that are carried by other individuals. So, for example, a male sacrificing himself to protect his sister’s offspring doesn’t make much sense from the perspective of individual fitness, but is explained nicely by the idea of genetic fitness.
Evolution only needs a mechanism for heredity. Typically, that means genes.
But not all DNA is genetic; some is outside any gene. That DNA is still inherited and so theoretically subject to evolution. A daughter cell also directly inherits some proteins, which is another possible non-genetic source of heredity.
Genes are the instrument of heredity and variation. However, the individual is the primary object of selection; phenotypes, not genotypes, are all that is visible to the “environment” for the most part. If a gene does not result in a phenotype which interacts with a particular environment, it doesn’t get selected for/against.
Aside form that, there is also the concept of epigenetic inheritance, wherein cellular traits which are not direct products of genetics can be passed on. These tend to only persist for a few generations, though, so it’s not known how important they are to evolution per se.
Are you talking about DNA that is not transcriped? While it is true that it has some functions, I don’t think any of those are relevant to levels larger than the DNA level itself.
Yes. I don’t know of any examples where it is relevant, but anything that is inherited is theoretically subject to evolutionary forces. Just pointing out a potential source of non-genetic evolution.
I think the term ‘gene-centric’ here is used in contrast against what would probably be called ‘trait-centric’ evolution. That is to say that rather than:
-Organisms with favourable trait X being more likely to survive, reproduce and pass on trait X
It’s:
-Populations with genes P and Q may produce traits that increase survival/reproductive potential (in a given niche), therefore genes P and Q are likely to prevail in the gene pool (where they may subsequently produce similar traits).
It’s also still wrong (or, perhaps more generously, inaccurate), as it’s not the genes themselves that matter, but gene alleles*. But even then, you still have to link the allele to a trait for it to matter in any evolutionary sense. An allele’s frequency in a population is going to be determined either by random chance (e.g., genetic drift), “selfishness” (e.g., an allele which is produced more frequently than other alleles for the same gene, regardless of any positive or negative effects it may have on the individual), or selection (e.g., the allele produces a trait which bestows an advantage or disadvantage to the organism in the organism’s current environment, leading to a higher likelihood of that individual passing on its genome – and thus the allele in question – to future generations).
In any case, while selection can, in theory, act directly upon an allele, it is the selection of inidividual phenotypes which primarily determines allele frequencies in a population, and thus drives evolution.
- “Gene-centric” evolution is not simply a restatement of how evolution works in the context of genes, but a statement that the primary object of natural selection is the gene itself, rather than the individual. Needless to say, I disagree with this concept, for a variety of reasons.
Are there people who think that there is no single unit of selection, that rather, selection happens at several different levels?
That would be interesting to read about.
-FrL-
Many evolutionary biologists would agree that there are multiple levels of selection (e.g., gene, individual, population, species, etc.). The debate usually comes in as to which level is the primary object of natural selection (that is, what does natural selection “see”, and therefore select from, when it does the selecting).
Yes, I was wondering if anyone thinks there is no primary object of natural selection–that selection occurs on several different levels* and that selection at one level can not (at least can not always) be reduced to terms of selection at other “lower” levels. If there were two levels of selection, neither of which could be described in terms reduced to selection at the other level, then there would be no such thing as a “primary object of selection.”
-FrL-
*Without the potential for reduction of one level to another level, of course, it’s a little problematic to call them “levels” but hopefully you see what I mean in any case.