As PhD research goes, Brian Wisenden was enviable, watching baby fish swimming swiftly through the clear waters in the Costa Rican tropical dry forest. By recording their growth and numbers, he hoped to look at their risks of being eaten. Instead, he witnessed something odd. Many groups were increasing in numbers. In these groups, some were smaller than others, suggesting they weren’t siblings (兄弟姐妹). Wisenden had accidentally discovered that the fish, called convict cichlids, adopt each other’s babies. Why would they do that, he wondered?

In the human world, we think of adoption as a selfless act. But in nature, its presence is puzzling. Taking on the burden of bringing up babies with no genetic link would seem to reduce an animal’s chances of survival or at least provide no gain. Yet, adoption is surprisingly common in the world.

Take the eastern grey kangaroo. Between 2008 and 2013, Wisenden followed the fates of 326 baby kangaroos in the National Park in Victoria and recorded 11 cases of pouch swapping. The circumstances behind some of these adoptions aren’t known, but four were straight swaps and another four occurred after a mother had lost her own baby.

How come? Before independence, baby kangaroos go through a period inside and outside their mother’s pouch. Following out-of-pouch forays, mothers normally sniff their young before allowing them back in, but Wisenden’s team suspect that during an emergency they may skip the sniff test, allowing a vulnerable baby to quickly climb in before fleeing from danger. Once inside the wrong pouch, the young may fake the mother’s odor, making them smell confusingly like her own progeny. So, poor baby recognition is the prime cause of “accidental” adoption.

Some of nature’s adoptions are, actually, driven by young looking for better prospects. In burrower bugs, for example, females lay a nest of eggs close to those of unrelated bugs. Mother bugs tend their developing eggs before they hatch, then feed their babies nuts from weedy mint plants. Finding nuts is a competitive business, so not every mother bug gets her fair share. And if the delivery rate isn’t up to scratch, clever young may abandon their mothers to join a better-fed group. That’s similar to behavior in several species of gull whose babies, if poorly fed, may leave home in search of better parents.

The consequences of adoption following mistaken identity can be dire. The true babies of adopting mothers were abandoned. But it can have remarkable benefits, not just for adoptees but also for adoptive parents.

It’s breathtaking to watch the delicate spring wildflowers come out from their blanket of leaves, bloom, develop and disperse (传播) fruit, all in a matter of a few short days or weeks.

Although they look fragile, these are tough little plants, each focusing its efforts on spreading its species. They have evolved to have a wide range of flower structures and colors, some with fragrances, attracting many different insect species to assist them in pollination (授粉).

There is one strategy (策略) that a surprising number of spring blooming native plants have evolved in common: seed dispersal by ants. As many as thirty percent of the spring flowering plant species in the forests of eastern North America have evolved to take advantage of this situation to benefit themselves. These species have evolved to provide food attached to their seeds to encourage ants to disperse those seeds. This food, called an elaiosome, is a specialized fat body whose chemical composition more closely matches that of the insects that ants prefer than it does that of a seed.

When a fruit opens to disperse its seeds, the elaiosomes are an instant attraction for ants. They take the seed with its attached elaiosome back to their nests for consumption there, but they just eat the elaiosome, their preferred food, and dispose of the seed on their trash pile. This tends to be an environment that is rich in nutrients, and will benefit the growth of the new plant. Just to make sure the ants don’t eat the seeds in addition to the elaiosome, some plant species have hard seed coatings that ants can’t really bite through.

This evolutionary adaptation is somewhat similar to the strategy of plants that have evolved to surround their seeds with fleshy fruits to attract birds to assist them with seed dispersal. Given the fact that there are fewer birds available in early spring to help with seed dispersal, it makes sense that the early blooming plants evolved to partner instead with the ants for this service.

Did you ever wonder how your Spring Beauty managed to pop up in new locations in your lawn or garden? Thank an ant!

We know animals have emotions. They can feel fear. We also think they feel love, since they have strong relationships with each other. So are animal emotions similar to our own? And do animals have a sense of humor? Do animals feel empathy? Does an elephant have consciousness? Can a dog plan ahead? These are some of the questions that deserve our full attention.

A parrot’s joke

Sally Blanchard’s parrot Bongo Marie didn’t get along with her other parrot, Paco. In fact, Bongo Marie clearly didn’t like Paco at all! One day, Blanchard cooked a chicken for dinner. She started to cut the chicken with a knife. “Oh, no! Paco!” Bongo Marie said loudly and laughed. Blanchard laughed, too, and said, “That’s not Paco.” “Oh.. no,” said Bongo Marie. This time, she sounded disappointed. Then the parrot laughed at her own joke.

Yoga dog

Jean Donaldson enjoys yoga, and so does her dog Buffy. While Donaldson does yoga, Buffy carefully places her toys on Donaldson’s body. If a toy falls, Buffy runs to put it back. Does this behavior have any real purpose? “She thinks it’s funny!” says Donaldson.

Animal laughter

Can dogs laugh? Recent research shows that dogs can tell each other when they want to play. They make a special sound — a kind of laugh. Psychologist Patricia Simonet recorded the sound. Then she played it back to dogs and studied their behavior. “All the dogs seemed to like the laugh,” says Simonet. So do animals have a sense of humor? If laughter is a clue, then perhaps the answer is “Yes”.

Life is very vivid to animals. In many cases they know who they are. They know who their friends are and who their rivals are. It is incredible that there is still a debate over whether animals are conscious and even a debate over whether human beings can know animals are conscious.