The last thirty years have seen some significant changes take place with respect to specific traits or characteristics within the porcine species. These traits, as described by geneticists, would be “days to 100 kg”, litter size, and “backfat at 100 kg”. If production systems are unwilling or unable to adjust to new biological potential who should define the limits that should be imposed on genetic selection? In the case of backfat and growth rate, the improvement appears to be very consistent over the past twenty-five years. Litter size has changed more aggressively in the past 10 years. Many factors have lead to this increase in litter size, and it appears that the Yorkshire has seen the most dramatic increase. Many factors have also lead to a decrease in days to 100 kg and decrease in backfat at 100 kg. Trends seem to be relatively similar between Yorkshire, Landrace, and Duroc.