South African farmer Alwyn van der Merwe said workers noticed several years ago that one of his tangerine trees was already stripped of fruit when the other trees were ready for picking. The same thing happened the next year, and the next. A farmworker finally solved the mystery when he saw baboons picking the tree clean. This one tree was making ripe tangerines three to four weeks ahead of all the others.
Van der Merwe said tests showed the fruit is sweeter and ripens faster. He produced more of the trees using grafts. His ALG Estates, a family citrus business north of Cape Town, will soon be exporting the tangerines, van der Merwe said.
The farmer believes the new variety is the result of a mutation, but one wonders what role the babbons selecting sweeter fruit played – if any…
Afarensis: Anthropology, Evolution, and Science 
“- but one wonders what role the baboons selecting sweeter fruit played – if any…”
What a great question – the role that humans played in the evolution of cereal crops is easily recognized, as is the role of insects in the evolution of flowering plants. These might be called macro-effects, but what more subtle effects have gone unnoticed? Squirrels, birds and other animals perform a constant selection in their foraging for foods, indeed, as anybody who owns a cherry tree can attest, there is great competition among birds to get the earliest ripening cherries. This competition has to have an effect in the long-term. It is evident that the world is so fruitful because of this selection process, carried on not only by humans but by all active foragers. Humans, as hunter-gatherers, undoubtedly preferred the fattest, most easily harvested grain heads long before the cultivation of these crops and this activity must have gone on for ages. Long before the first irrigation canal was dug the importance of water’s role in plant growth must have been appreciated and the first irrigation was undoubtedly the diversion of streams to native crops. This may have even preceded permanent residency. By the time that our technology advanced to allow cultivation it must have been evident to our ancestors which grains were the most suitable for their purposes and what it took to provide for them – cultivation may not have been a sudden revolution but one that developed gradually from long practice. And the importance of fertilizers was no intellectual leap – as a child, growing up on a farm, long before I understood the importance of nitrogen as a nutrient, I was impressed that plants grew more vigorously around cow-patties.
I am aware that plant geneticists and anthropologists have made great strides in tracing the history of cultivation into the past – one thinks of the successful identification of the early predecessors of maize and wheat and the identification of early cultivation sites, but could investigations into the patterns and clues that guide foragers provide further insights into the evolution of plants and animals and the development of purposeful cultivation?
Lots of conjecturing about selection, but no mention of why, for example, baboons preferentially eating a sweeter and earlier-ripening tangerine would selectively favor sweetness and early ripening. What sort of adaptationist hypothesis(es) about that or about birds competing for early cherries, could one actually test? The competition mentioned in both cases is among the eaters, not the eaten.
Good point. Earlier ripening and increased sweetness would have to provide some sort of reproductive advantage to the tree…
Or not: a single organism does not evolution make. We don’t know the range of variation of fruiting time in the original population, and any selective pressure now is being applied by the farmer in assisting its reproduction via cloning. We don’t even know if it breeds true. So I think it’s a mistake to talk about evolution and/or natural selection of the tree with respect to the one instance we have. What would be interesting is to find more such trees, perhaps sprouted from seeds spread by the baboons in their feces (or by spitting out seeds) to see whether they have a similar time of fruiting.