Friday, September 21, 2012

Serious Spines Series 3

Why do some cactus have serious spines and others hardly any at all? The argument is that spines evolve to protect the plant, but then the animals that eat the plant either evolve to eat the spines also or somehow avoid the spines. Another theory is that the spines shade the plant from the hot summer sun. If that is the case, then why do some cactus have huge spines like this one and others smaller spines that hardly provide shade? I think we need to look elsewhere for a reason and avoid ad hoc reasoning.

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