Daily Times

As believed by Scott Gilbert, developmental biologist at Swarthmore College, the “egg engages in a dialog with the sperm rather than locking it down.” So, fertilization is not actually a conquest, but more like a fair race.

After much research, it has also been proven that eggs tend to attract a particular kind of sperm if given the chance.

This is in sharp contrast to what scientists have been portraying for decades, sperm as active fighters battling their way towards a passive egg.

On the contrary, semen does not appear to have the same ability to detect bad genes, researchers found.

Interestingly, the research is in sharp contrast to Mendel’s Law that suggests fertilization in random and shows how scientists have long projected traditional gender roles onto their work, leading to the portrayal of eggs as passive and sperm as active.

What underlies all of Mendel’s laws is the idea of randomness. Scientists believe that it is up to chance which sperm will fertilize an egg and which combinations of alleles the offspring would have. That is, of course, after the sperm has proven itself to be the strongest and most enduring swimmer of them all. But the point is, the egg has no say in this. It sits passively waiting to be fertilized.

In an article that appeared in Quanta Magazine, Joe Nadeau, principal scientist at the Pacific Northwest Research Institute outlined why he believes eggs are an active player in reproduction.

There is no evidence of how the eggs and sperm might do this but Dr Nadeau believes there are two possibilities.

One is that the rate of metabolism of B vitamin, such folic acid – which is an important signalling molecule – is different in sperm and eggs.

As part of his work, Professor Nadeau bred female mice carrying one normal and one mutant copy of a gene that increased the chance of getting testicular cancer.

The male mice all had normal genes.

The resulting offspring followed Mendel’s rules and there was a random dispersal of the mutated form among offspring.

But in the second experiment, Professor Nadeau reversed the breeding.

He gave males the mutant copy of the cancer gene while the females had the normal version.

Only 27 per cent of the offspring had the mutant variant, compared to the 75 per cent they expected to see.

This selection process can spur the evolution of new recognition proteins, eventually resulting in reproductive isolation and, in some cases, the creation of new species altogether.