Being able to tell human faces apart is a skill that almost every person has, although some are far better at it than others. But a new study from the journal Scientific Reports says that this is not just a skill that humans possess. Even fish can do it.

Following up on research studying different species’ abilities to recognize human faces (sheep, dogs, cows, horses, and birds have all been tried), the researchers from the University of Oxford and the University of Queensland decided to pick an animal that does not have an evolved neocortex (大脑新皮层), the part of the brain that processes sight and sounds, and does not have a close relationship with humans. That way, there would be no reason why these test subjects would have a past history of identifying human faces. So they picked the archerfish, a reef fish variety that shoots water into the air to knock its prey(猎物) out of the sky. They used this adaptation to have the fish spray water at a face on a monitor hanging over their tanks for a reward. Most of the fish were able to pick out their learned face, even when colours were taken away or methods were used to make the face shapes unclear.

This study gives more backing to the hypothesis (假设) that differentiating between faces is not just a skill that big-brained organisms are born with. It is possible that a good portion of recognizing faces is learned over time. The development of the neocortex may contribute only to quickly process a large number of faces in varying situations. But more work needs to be conducted to find a deeper link to this possible learned behaviour. The subject(实验对象) of this study was very small—only eight fish were used altogether. Also, the faces displayed on the monitor were only white, female faces from a German database, shown in a frontal view, with no expressions. Other animal trials have shown that some species, like pigeons, respond more to differing angles and varied expressions.

Feeding bread to the ducks is a fond pastime for many of us, reminding us of our happy childhood trips to the local park. But did you know that bread actually poses a danger to birds, as well as the environment? Eating it can cause our feathered friends to develop a condition called Angel Wing, which is when too much bread makes birds’ feathers grow too quickly. This additional weight puts a strain on their muscles, causing their wings to twist and drop open, and if not treated fast, they can lose the ability to fly.

“Angel Wing can be remedied if we reach birds before it has developed too severely,” says Caroline Simpson, a trustee of UK charity Swan Lifeline, which has rescued and treated more than 30,000 birds over the last 20 years. “Otherwise the consequence can be awful—such as amputations(截肢)of the wing.” Adult swans can also develop gut and heart disease, so it’s important we do our bit to prevent this by feeding wild birds with the right kind of food.

Bread can also cause harmful changes to the natural ecosystem. Rotting bread at the bottom of   rivers and lakes allows bacteria to breed, spreading disease and attracting rats and other vermin to our waterways. It can result in algal(藻类的)blooms and the presence of a mould(霉菌)called Aspergillus too, which has the potential to kill waterfowl(水禽)and other wildlife if it gets into their lungs.

But this doesn’t mean we have to stop fun trips to feed the ducks. Giving birds the right food-like frozen peas, sweetcorn and lettuce leaves-is good for both them and the environment. So, next time   you visit your local park, take a healthier alternative with you and do your bit to protect our precious wildlife.