Humans have not fairly measured ape intelligence, so we don’t really understand how smart they are, a team of researchers has asserted.

The authors claim that tests are biased such that they measure performance more than they measure actual aptitude, according to a paper in the journal Animal Cognition. Among the problems that make it difficult to test an ape’s intelligence in an equitable manner to humans is how differently apes and humans are prepared for experiments — specifically in their background.

This team compares the difference between humans and apes to the differences between different groups of humans. With people, factors like health and education, tied to economics, play a role in how well someone performs on a test designed to measure intelligence.

“We now know that intellectual performance in our species is a function of gene-environment interactions: impoverished environments have systematically deleterious effects on mental development,” the study say.

Similarly, people who are raised to be more familiar with certain concepts will perform better when tested on them.

This connects to apes because, for example, in some studies apes that had lived in isolation, in ways that would not give them much exposure to human non-verbal cues, were tested on their social skills against children who had lived their whole lives with exposure to those cues. Therefore the human children would be better versed in those social cues going into the experiment and have an advantage.

“Yet, today, researchers routinely report in the most prestigious journals claims that human children, even as young as 12 months of age, are inherently superior in social intelligence — the skilled negotiation of social interactions — to our nearest living relatives, the great apes,” the researchers say.

In those studies they examined, however, the scientists had concluded that evolution had made the human test subjects intellectually superior.

animal-17474_1920 A group of scientists says research is biased against apes. Photo: Pixabay, public domain

The University of Portsmouth explained in a report on the research that behind the poor measurements of ape intelligence are “wishful thinking and flawed science.” But why would humans be so biased against other apes?

“The fault underlying decades of research and our understanding of apes’ abilities is due to such a strongly-held belief in our own superiority, that scientists have come to believe that human babies are more socially capable than ape adults,” researcher David Leavens said in the report. “As humans, we see ourselves as top of the evolutionary tree. This had led to a systematic exaltation of the reasoning abilities of human infants, on the one hand, and biased research designs that discriminate against apes, on the other hand.”

According to the paper, when humans perform better in an experiment than apes, it is used as confirmation that the humans are smarter. When apes perform better, however, it might be said that the results are inconclusive.

The researchers have compared the bias toward humans over apes to previous bias in scientific studies from decades ago, in which researchers thought northern Europeans were more intelligent than other races and designed flawed experiments whose backed up that idea.

“In examining the literature, we found a chasm between evidence and belief,” researcher Kim Bard said in the university statement. “This suggests a deep commitment to the idea that humans alone possess sophisticated social intelligence, a bias that is often not supported by the evidence.”

One possible remedy for a flawed experimental design would be for humans to foster apes, giving them a background more similar to human children, or to train them in the skill that they are being tested on, so as to give them more experience leading into an experiment.

“Where differences have been reported between ape and human groups, the relevant factors accounting for these differences (environmental, genetic) remain unknown,” the paper says. “Thus, to claim a ‘species difference’ in social cognition between apes and humans, at our present state of knowledge, is to promulgate the same kinds of prejudices that hereditarians evinced in the early history of biometric approaches to the study of intelligence.”

gorilla-622056_1920 A group of scientists says research is biased against apes. Photo: Pixabay, public domain