To the tune of Mary Hopkin's iconic 60s hit, Those Were the Days, a team of UC animal scientists ask whether those bygone times people remember nostalgically would be up to the challenge of feeding the world today.

"People have a romantic image of farming in the past," said Alison Van Eenennaam, UC Cooperative Extension specialist in the UC Davis Department of Animal Science. "It may be remembered as bucolic, but there wasn't enough food being produced to cope with world population growth."

Van Eenennaam, an expert in animal genomics and biotechnology, rewrote the song and posed the question, Were those the days?, with historical photos of Americans...