Before human beings were around, how did lemon seeds get dispersed? Do other animals eat them?
Lemon seeds become dispersed just like any other seed becomes dispersed. The fruit falls from the tree, the fruit becomes eaten or it decays, and what’s left is the seed.
I would imagine some animals ate the seed. The seeds that weren’t eaten became part of the earth and started growing.
Yes, I understand how seeds are dispersed. My point is that lemons are almost inedible. From an evolutionary standpoint, what is the use of nasty fruit. How did they survive? Why didn’t they evolve more palatable fruit? Who ate the damn things before people learned how to make pie?
to answer the original subject:
me.
They are only almost inedible to humans. You have to remember that animals have varying tastes. Herbivores can’t be as choosy when eating, since a good portion of their food supply is off-limits, so they probably ate most of the lemons. The lemons that weren’t eaten just decayed until the seeds were exposed.
I eat lemons. I also eat hot peppers. Some people cannot tolerate the heat from some of these peppers, but everyone has different tastes. I absolutely HATE grapefruit, I cannot stand the bitter taste, and if I didn’t know better, I might think that no one would eat them.
A friend of mine (when I lived in Boise) that had goats used to feed them all kinds of leftovers, and I distinctly remember seeing the goat eat a quartered-up lemon.
This is kind of off the topic, but how toxic is citric acid? How many lemons would you have to eat before it began to form ulcers? I like lemons myself, and I want to know when to say when. 
::raising hand::
Maybe 9-10 dozen per year, cut in half, liberally salted. Perhaps three times that in limes, I like limes better. We can get fresh limes in New York the size of softballs with paper-thin skins and few seeds and very juicy. Lemons more often have 4mm thick skins, 3/4 zillion seeds, and often border on bone dry. (Still, sometimes you just need that intense sunshiney lemon taste that even a lime doesn’t have).
I eat lemons & limes the same way I eat oranges. There are about eight zillion other so-called foods that I would put higher on the inedible list than these tangy fruits.
As for toxicity, it can be generally said that throwing your body’s pH too far out of whack isn’t a good idea, especially if you already have hyperacidity issues like GERD. Lemon juice has a pH of about 2, or about 10% the “strength” of stomach acid (pH ~ 1). However, citric & ascorbic acids are generally considered the safest of all commonly used food additives. They are both potent antioxidants (a chemical that keeps other compounds from being oxidized- i.e., turning brown or rancid).
From Phys.com:
I would hazard to guess that if you consumed too much of anything too acidic, your digestive system would let you know about it by sending you to the kitchen for a heaping helping of milk of magnesia.
Personally, I’d be more concerned about those Big Macs you eat for lunch every day.