What came first? The chicken or the egg? Really?
FearGod, every sexually reproducing organism on earth had a mother and father. Every human baby (until recently) had a mother and father. Every mother and every father grew from a baby, and had a mother and father of their own.
Science does not disagree with this. And this is not inconsistent with evolution.
He's making the chicken or egg argument for mammals basically. What came first, the first parent or the first baby?
It is challenging to think how so many complex processes did get going though.
I know. I'm trying to get him to think a little harder about his objection before I try to be helpful. But here goes;
Part of the problem is the conception of type, species, or human; all meaning the same thing, that we are all of one kind, and all non-human are not of this kind. It is an illusion that the human type can be defined in such exclusive terms. If we were able to sample humans of 100, 1000, 10000, 100000, 1000000, years ago, they would all be humans, and each population would be very different in terms of gene frequencies and we would define a new type, a different species.
Every population of humans would be reproductively compatible with every other population that was next to it, temporaly speaking. But the populations at the end of the spectrum would not be.
So yes, every baby needs parents, and every parent was a baby, and all parents and offspring are very similar genetically and can't give rise to something much different. But recombination necessitates that offspring will be a tiny bit different, And 100000 differences add up from start to finish.
Think of a stairway with 10,000 steps. From any one step you can only get to the one above or the one below. Someone standing on the bottom step cannot take one step and get to the top. It is impossible. But after 10,000 steps you can no longer even see the bottom.
This may be helpful. By looking at the problem spatially rather than temporally we find very similar situation with 'ring species.'
Ring species - Wikipedia, the free encyclopedia
A classic example of ring species was the Larus gulls' circumpolar species "ring". The range of these gulls forms a ring around the North Pole, which is not normally transited by individual gulls.
The European Herring Gull (L. argentatus argenteus), which lives primarily in Great Britain and Ireland, can hybridize with the American Herring Gull (L. smithsonianus), (living in North America), which can also hybridize with the Vega or East Siberian Herring Gull (L. vegae), the western subspecies of which, Birula's Gull (L. vegae birulai), can hybridize with Heuglin's gull (L. heuglini), which in turn can hybridize with the Siberian Lesser Black-backed Gull (L. fuscus). All four of these live across the north of Siberia. The last is the eastern representative of the Lesser Black-backed Gulls back in north-western Europe, including Great Britain.
The Lesser Black-backed Gulls and Herring Gulls are sufficiently different that they do not normally hybridize; thus the group of gulls forms a continuum except where the two lineages meet in Europe.
