How are goats able to eat poisonous leaves like sumac, ivy and oak?
In: Biology
The chemical in that causes skin irritation in humans is called *urushiol*. The same chemical is present in poison ivy, sumac, and oak. It’s not actually a poison – it’s an oil that can bind to proteins on the outside of cells, and for that reason scientists suspect that it evolved as a protection against microbes, *not* against being eaten by larger animals.
In humans, it triggers an auto-immune response (it tricks your immune system into thinking the cells that have touched the oil aren’t yours), but not in other animals.
So, in short – goats, cats, dogs, birds, etc simply aren’t allergic to it.
The only reason I know this is because I got into a *serious* patch of poison ivy cleaning up after tropical storm Isaias last week, and I’ve been doing some reading while I scratch myself raw.
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