http://www.nature.com/ncomms/2016/160129/ncomms10496/full/ncomms10496.html H Miller et al, 'Human predation contributed to the extinction of the Australian megafaunal bird Genyornis newtoni ~47?ka' This is eggs-actly what I needed 40 years ago for university Intro Biology. It is a simple example of how decreased survivability of offspring reduces the fitness of a population. Early humans ate lots of the very large eggs produced by this species. Fewer eggs means fewer nestlings can survive long enough to reproduce. Of course I am assuming the stated conclusion in the paper is verifiable. But all other things aside, I think non-science folks do much better with "homey" everyday examples. What could be more down to earth than cooking and eating eggs? 47000 years ago. Ignoring the fact that you would have to fight off a 200kg bird every time you wanted eggs with your morning paper.