[partyboat1586]

The sugar in fruit is not poisonous and encourages you to eat it so you can carry the seeds to another location but you're not meant to chew or digest the seeds. Nuts are similar to seeds in this way.

>Cancer can't occur, unless there are unsaturated oils in the diet.

This does seem like a dubious statement.

[labawi]

Many plants have seeds with ample sugars, fats, and/or protein, yet no nutritious or enticing exterior. Is the preferred evolutionary strategy falling to the ground and poisoning anything that dares to eat you?

Obviously spreading doesn't work if all of the seeds are eaten, but I've seen walnuts spread far and quite effectively (multiple saplings yearly) - presumably by crows failing to crack a nut, mice not eating some of their gatherings or similar methods.

BTW the fruity part of walnuts is definitely poisonous, as are the leaves and maybe even the wood, but the nuts are fine and nutritious.