Re: Do humans come from spiders??

Spiders and people do have some things in common, but people aren't descended from them. In fact, if you look carefully you'll see that there are far more differences between your pet spider and you than there are similarities. For example, your skeleton is on the inside of your body, but her skeleton is on the outside. She has eight limbs while you only have four. She has more eyes, too -- and none of them are shaped like a human eye at all! You both have mouths, but she doesn't have teeth like you do; she has a pair of external leg-like structures called chelicerae that hold and poison her prey while she spits digestive juices onto them. And your spider's hair may look sort of like yours, but her hair is made from a material called chitin, which is a very complex sugar. Your hair is made of keratin, which is a kind of protein. There are so many differences between you and your spider because spiders are arthropods and people are vertebrates. Arthropods and vertebrates aren't very closely related at all. References: Barnes, R. D. 1987. Invertebrate Zoology, Fifth edition. Philadelphia: Saunders College Publishing. Barnes, R. S. K. (ed) 1998. The Diversity of Living Organisms. Oxford: Blackwell Science. Wainwright, S. A., W. D. Biggs, J. D. Currey, and J. M. Gosline 1976. Mechanical Design in Organisms. Princeton: Princeton University Press.