Which came first, adults or babies?

[littlemslazybones]

This is the question my son caught me out with while I was driving.

I thought he was just re-checking the basics so I explained that mummies have babies and so adults came first but he was very unimpressed. He has asked, in a chicken and egg fashion, who raised the first babies to adults who then had the babies.

We seem to have stumbled into evolution and I'm looking for a way to explain this to him in a way that will makes sense to an almost 5 yo and the Usborne first encyclopaedia we have is sadly lacking.

The online resources seem to be set up for older children. Could anyone recommend a first step with this? Every time I think I've got it straight in my head and that I can explain this usefully, maybe starting with the peppered moth as a starting point, I think there has to be an easier way.

And now he has got it in his head it's all he's going on about.

(I couldn't think of the proper place to put this but hoped, with all the teachers and parents of similar aged children on this board I could get some good advice here)

(The Usborne encyclopaedia I mentioned above is a science encyclopaedia).

The very first organisms didn't change from babies to adults, they were just adults when they formed. So they didn't need anyone to look after them.

After a very long time, some of the creatures got steadily more complicated, and eventually began having babies that needed to be looked after. So the very first baby that needed to be looked after came from an adult that didn't need to be looked after.

All very gradually, of course

If you need some more on abiogenesis, I can help later =P

Thanks Sunscorch, yes that makes sense. I'll start from simple cells rather than primates (I don't know why I was getting distracted by those moths )

Right, so at the risk of looking more like a doom brain, for my own peace of mind now, when we do get to primates and we shuffled slowly over (65?) million years through the various links to homo sapien, did the various small mutations occur in the parent which were then expressed in those individuals or did those mutations occur in the parent which were then passed down and expressed in the child or did the mutations occur randomly at conception?

Or, none of the above? Sorry, it's stuck in my head now.

Either the mutations occurred in the egg cells, or the sperm-producing cells of the parent and were thus passed on to the children and expressed there (unlikely), or the mutations occured early in the development of the child and expressed as the child developed.

Mutations that occur in adult cells only ever have a local effect, and aren't passed on unless they happen in the gamete-producing cells.

It's also worth noting that some expressions of behaviour aren't dependent on mutations, as such, but can be a result of novel combinations of alleles from the parents.

Once the child grew up and was expressing the new alleles, or new combinations of alleles, they will then be passing them on to their children. If the new expressions are beneficial, they will tend to be passed on more often than detrimental alleles, and that's basically evolution by natural selection.

You have been a big help Sunscorch. Thanks for your time.

No probs. Apologies for the mixed tenses that I just noticed xD