Lacking Brains, Plants Can Still Make Good Judgments About Risks
Plants may not be getting enough credit. Not only do they remember when you touch them, it turns out that they can make risky decisions that are as sophisticated as those made by humans, all without brains or complex nervous systems. And they may even judge risks more efficiently than we do.
Those are the findings of a study published Thursday in Current Biology. Researchers showed that when faced with the choice between a pot containing constant levels of nutrients or one with unpredictable levels, a plant will pick the mystery pot when conditions are sufficiently poor.
“It raises a question, not about plants, but about animals and humans, because if plants can solve this problem simply,” then maybe humans can, too, said Hagai Shemesh, a plant ecologist at Tel-Hai College in Israel who worked on the study. “We have a very fancy brain, but maybe most of the time we’re not using it.”
“这提出了一个关于动物和人类，而非植物的问题。因为如果植物可以简单地解决问题”，那人类或许也能做到，参与了这项研究的以色列特尔海学院(Tel-Hai College)植物生态学家哈加伊·谢梅什 (Hagai Shemesh)说。“我们拥有奇妙的大脑，但我们在大部分时间里或许并未使用它。”
In a set of experiments, Dr. Shemesh and Alex Kacelnik, a behavioral ecologist at Oxford University, grew pea plants and split their roots between two pots. Both pots had the same amount of nutrients on average, but in one, the levels were constant; in the other, they varied over time. Then the researchers switched the conditions so that the average nutrients in both pots would be equally high or low, and asked: Which pot would a plant prefer?
When nutrient levels were low, the plants laid more roots in the unpredictable pot. But when nutrients were abundant, they chose the one that always had the same amount. The plants somehow knew the best time to take risks.
“They are less than pea brains, they are no brains,” said Dr. Kacelnik. “But they did it.”
Evolutionarily, this makes sense for a plant trying to survive.
“In bad conditions, the only chance of success is to take a chance and hope it works out, and that’s what the plants are doing,” said Nick Chater, a behavioral psychologist at the University of Warwick in Britain, who was not involved in the study.
“在糟糕的条件下，成功的唯一机会就是放手一搏并期待有好的结果，植物就是这样做的，”英国华威大学(University of Warwick)的行为心理学家尼克·沙特尔(Nick Chater)说。沙特尔没有参与该项研究。
This complex behavior in a plant supports an idea, known as risk sensitivity theory, that scientists have long had trouble testing in insects and animals. It states that when choosing between stable and uncertain outcomes, an organism will play it safe when things are going well, and take risks when times are hard.
It explains why people gamble more when they’re losing money, or why birds that must eat enough food to survive a cold night will forage not knowing what they’ll find, rather than settle for a certain, but insufficient amount of food.
But the theory doesn’t explain, for instance, why people would prefer a 25 percent chance of losing $200 to a guaranteed loss of $50, but would also prefer to buy insurance for $50 to cover a 25 percent risk of losing $200, which is a classic conundrum for scientists studying risk. The mathematical outcome is the same, but they “feel” different.
Dr. Kacelnik said that instances like this, when data defies risk assessment theory, don’t necessarily mean it’s wrong; it just means the tests aren’t sensitive enough. The simplicity of plants makes it much easier to create a proper test for at least one reason: Plants don’t worry about feelings.
How brainless pea plants evaluate risk is still unclear, but Dr. Shemesh thinks they must be following simple rules, not reasoning. “Even if you have no cognition or fancy nervous system, you can still get some pretty complicated behavior.”
Perhaps, we all should embrace our pea brains.