Sex is defined by cell type (females big immobile ones,and males small mobile ones) the question is which came first prokaryotes or eukaryotes? Eukaryotes came from prokaryotes. So males came first. Prokaryotes are small cells that are mobile like sperm that can self reproduce they even have a tail, eukaryotes are big cells . I'm aware sperm is technically eukaryotic but both originated from Prokaryotes which can be considered a male cell. The ultimate question is which came first sperm or eggs , the answer is clearly sperm at least in concept meaning small mobile cells came first so males came first. The oldest known fossilized prokaryotes were laid down approximately 3.5 billion years ago, only about 1 billion years after the formation of the Earth's crust. Eukaryotes only appear in the fossil record later, and may have formed from endosymbiosis of multiple prokaryote ancestors. The oldest known fossil eukaryotes are about 1.7 billion years old. So males came first If eukaryotes hadn't have come along we would all produce in a very typical male way as females would probably not exist at least in concept. If that makes any sense . Smaller faster cells originated before fat lazy cells. Does that make any sense? Sperm can be considered older than eggs. I'm no biologist but I'm pretty sure eggs aren't mobile and aren't small like sperm. So is prokaryotes like a proto concept for sperm? Or am I getting this wrong meaning just because it looked like sperm doesn't really mean anything,  but than why does it have all the male characteristics . And why aren't eggs mobile?  Why are eggs big and not small like prokaryotes and sperm?  Could sperm be said to be older in concept and therefore males are older?

I think you are conflating a bunch of different ideas here

1) Prokaryotes came first before eukaryotes. they are unicellular and (largely) reproduce by binary fission which is of course asexual (although gene transfer can occur horizontally).

2) Prokaryotes are not in any real sense the precursors of (or even analogous to) sperm of eukaryotes. Yes, sperm are typically small, motile cells and so are many prokaryotes, but that's about it.

3) What came first the sperm or the egg? Well it's more a case that anisogamy (=differentiation of gamete size) evolved between mating types, so I guess the real answer was that it was simultaneous. We basically define male and female gamete types by their relative size, meaning as one gets relatively bigger the other gets relatively smaller.

So the real question is .. what drove the evolution of anisogamy? I'm not really an expert in that but the wiki page at least gives an overview of the leading hypotheses

Last edited by Alistair Wilson (3rd May 2016 11:41:32)