[choilive]

Its the same evolutionary patterns that plants went through.

Most mushrooms are edible because their spores can pass through the digestive system of most animals, thus allowing them to spread.

Other mushrooms developed toxins to protect their fruiting bodies - often the biggest threat isn't larger animals, but insects. Toxins that are neurotoxic to insect nervous systems, happen to cause mostly "harmless" psychedelic trips to our brains. Other toxin mechanisms happen to be deadly to both insects and humans.

As proof of this evolutionary arms race, there are fruit flies that have developed resistance to amatoxins.

[ajb]

It may be worth mentioning, for anyone who didn't know this already; that the fruiting body, which is what your normally see, isn't most of the mushroom. The rest of it is in the ground, or in something else like a dead log or live tree. So the organism can afford the fruiting body to be eaten, if it serves the purpose of spreading spores.

[uplifter]

This relates to why you will often see multiple mushrooms of the same type blooming at the same time in a ring pattern: the edge of the ring is the periphery of the linearly, radially expanding mat of subterranean fungal fiber weave, which produces fruiting bodies at its edges.

[seizethecheese]

> Toxins that are neurotoxic to insect nervous systems, happen to cause mostly "harmless" psychedelic trips to our brains.

True for coffee as well (if you substitute psychedelic with a more appropriate word).

[choilive]

Yep, thats a good one. Caffeine is deadly to insects, but a mostly safe stimulant for us. Nicotine also comes to mind. Plants have developed tons of defense mechanisms that are deadly to one class of animals, but useful or only mildly deterrent to others. Avians are immune to capsaicin, but an irritant for mammals.. except for some hairless primates.

[cluckindan]

Insects have the some of the same neurotransmitters as mammals, but they can be relaying different things. For example, dopamine is not used for reward learning, but for aversion learning and pain.

[card_zero]

Even in humans it has multiple roles, such as for movement (as in Parkinson's disease), and various signals around the body, excreting salt, calming down T-cells.