Where do scientists often look to find evidence of glacial periods in
earth's past?

Normally this would be found near the coasts of Africa and Antartica

it would be the percentage of food eaten by the flock

i remember doing this lab

in 1859, charles darwin set out his theory of evolution by natural selection as an explanation for adaptation and speciation. he defined natural selection as the "principle by which each slight variation [of a trait], if useful, is preserved".