Many animals can. There are a gene for it, humans don't have it. There is a lot of speculation as to why, but nothing really stands out (possibly just random chance - if you eat enough there is no advantage to keeping the gene and in turn no loss from losing it. However I'm unable to rule out other possibilities) https://pmc.ncbi.nlm.nih.gov/articles/PMC3145266/ is a really interesting survey of the issue across many different species.