"The same conditions must have selected for sticking together as a positive survival trait among our ancestors."
I wonder if this sentence is grammatical.
I actually think we don't need 'for' in this sentence.
"Select for" is scientific jargon, used when people are talking about natural selection. The author is trying to say that those of our ancestors who had a greater tendency to stick together were more likely to survive and reproduce. If this tendency was heritable, i.e. able to be passed down to offspring in genes, it would become more and more common in the population over time.
Last edited by probus; 09-Sep-2013 at 13:14.