I suppose that it is somewhat plausible that single-celled creatures found it advantageous to merge with one another before dividing – a bit more variety in the genome, dontcha know? But when it comes to complicated creatures like whales, cattle and humans, even if we grant common ancestry, getting the gametes together requires some very special plumbing. The male thingy will do nothing to contribute to reproduction unless the female thingy comes into being simultaneously. The appearance of design is pretty hard to ignore. These organs were made for each other. Special creation is easier to credit. Dawkins calls my kind of thinking, “the argument from personal incredulity”. I think it is an excellent argument. Random mutation and natural selection? Puhleeze!
You’ve got these male mammals with an extra appendage. They can’t reproduce unless they encounter a female able to accommodate them – or vice versa, mutatis mutandis. No matter which of these mutants appears first, he or she is going to be extinct in short order, unless a complementary mutant fortuitously shows up – with all the necessary pheromones and what not.
Darwinians have over-developed organs of credulity. If your world view forces you to reject the idea of a designer (as poor old Lewontin’s does), you have to believe some startling stuff.
Now, the fact is that no scientist (or theologian, for that matter) has any idea of how precisely Life began. What is more, theories about how one species gives rise to another species are speculative in the extreme. It seems to me that in the absence of hard evidence, not provided by the fossil record, Occam’s razor has sliced away RM & NS. They are the forbidden entities.