Hunting in savanna-like landscapes may have contributed to brain planning circuits. The terrestrial environments are full of obstacles and occlusions and offer prey areas for hiding and protection against predator attacks.
In the film The Hobbit 2012: An Unexpected Journey, there is a central scene in which Gandalf, Bilbo Baggins, and a group of orcs are chased through a classic New Zealand landscape. For the neuroscientist and engineer at Northwestern University, Malcolm MacIver, the scene is an excellent example of the kind of inconsistent landscape – littered with trees, bushes, boxers, and rolling hills – that may be developing greater intelligence in humans compared to theirs Ancestors were shaped by water. In particular, it falls into a "goldilocks zone" – not too sparse and not too dense – which favors strategic thinking and forward-looking planning and, according to MacIver's latest article, leads to the development of "planning" circuits in the human brain in natural communication.
This latest paper builds on previous research. As early as 2017, MacIver and several colleagues published a paper that suggested an unusual hypothesis: these ancient creatures, who first crawled out of the water onto land, may have done so because they found that looking through the air was one Gießen has "informative advantage". The eyes can see much further in the air, and this increased visibility could lead to food sources near the shore. MacIver and its lead author, paleontologist Lars Schmitz of Claremont Colleges, argued that this in turn drove the evolutionary selection of rudimentary limbs and enabled the first animals to get from water to land.
This hypothesis arose from his research on the black ghost knife fish of South America, which is a nocturnal hunter that generates electrical currents in the water to capture its surroundings. After building a robotic version of the knife fish with its own electro-sensory system, he found that the volume of space in which he could see prey (water fleas in this case) was roughly the same as a fish whose hunt for sight is water fleas . It turned out that water absorbs and scatters light, which limits the range of the light: usually 10 to 2 meters compared to 25 to 100 kilometers of light in the air.
Our nearsighted inner fish: vision explains why our fish ancestors came ashore.
Increasing the size of the eyes would cause the high beam to turn on in fog so that the creatures can see further. However, the eyes also need a lot of energy to maintain them, which makes such a development evolutionarily costly for ancient aquatic life. But bigger eyes would give the air a huge evolutionary advantage and make the cost in an terrestrial environment an acceptable compromise, MacIver argued.
MacIver and Schmitz therefore searched the fossil record for evidence of an increase in eye size during the critical transition from water to land. They found that during this transition period, the size of the eyes tripled in about 12 million years, from 13 millimeters before to 36 millimeters afterwards. What was even more fascinating was that this increase started before the full transition from water to land was completed. This indicated that those aquatic beings who had learned how to put their eyes over water like a crocodile to find new food sources on the nearby bank had encountered "the gateway to terrestriality," MacIver told the quantum in 2017. Magazine.
The Goldilocks Zone
MacIver is now back with an even more provocative hypothesis: The geometry of certain habitats shapes the evolutionary selection pressure in predator-prey contexts. "The basic idea is that open spaces – open grasslands, flat plains – are just speed games that the predator prefers because they are larger," MacIver told Ars. "Enclosed spaces – dense forests or jungles – prefer simple strategies to cover We use a measure of complexity to show that both habitats are of low complexity. " This measure of complexity is lacunarity, a geometric term used to describe how patterns fill space.
The complexity of "Sweet Spot" is, according to MacIver, a landscape like that shown in the Hobbit chase or the Botswana & # 39; a Okavango Delta, both of which have open grasslands and moss zones littered with clumps of tree and similar foliage. "Neither speed games nor running for cover maximize survival in this zone," said MacIver. "But planning – what I mean by imagining future paths and choosing the best based on what you think your opponent will do – gives you a significant advantage." And this planning requires the kind of advanced neural circuits typical of the human brain.
The Okavango Delta in Botswana has an inconsistent landscape that is a good example of the "goldilocks landscape" in which the ability to plan leads to an enormous survival payout.
A chase in The Hobbit: An unexpected journey takes place across a New Zealand landscape that looks very similar to the "Goldilocks Zone".
MacIver and his northwestern colleague and co-author Ugurcan Mugan performed numerous supercomputer simulations that showed that further consideration (MacIver's original theory) is necessary for the planning to be evolutionary, but it is not enough. Rather, it requires a combination of distant views and complex landscapes. This in turn could have led to the development of one of the most difficult cognitive operations: the future vision.
MacIver and his team next created new predator / prey simulations to test prey survival rates using two different strategies. The first was habit-based and was similar to entering a saved password when prompted. The second was plan-based and included the ability to imagine multiple scenarios and choose the ones with the best chance of survival. They used a simple landscape with no visual barriers to simulate a water environment, and added different objects with different density distributions to simulate land.
The results: In the simple water and land simulations, regardless of the strategy used, the prey showed low survival rates, which shows that it had no evolutionary advantage to plan in environments that were very open or too tightly packed. In the first case, it is best to escape the predator. In the latter case, there are too few clearly available paths and the densely packed environment hinders how far the prey can see.
However, an inconsistent landscape in the Goldilocks complexity zone showed a huge increase in prey survival rates based on the planning strategy compared to the habit-based approach. The MacIver team has developed an online game to illustrate how different landscapes (coral reef, jungle, savanna and open water) affect our ability to plan and avoid a stalking predator. (You can play it here.)
Enlarge /. Screenshot of MacIver's online game that shows how different landscapes affect the ability to plan and evade a predator.
YouTube / northwest
Now MacIver is seeing evidence of the Goldilocks Zone everywhere, including films like The Hobbit. "The use of space (in the chase) was just fascinating with this interplay of opaque and open spaces," said MacIver. Although he hasn't figured out how to measure the exact gap in the landscape shown in this sequence, his guess is that it would fall very close to his goldilocks zone.
It was probably not a conscious decision by the filmmakers; MacIver sees this as an intuitive understanding of what constitutes an exciting chase. "It's about looking forward to something that's so powerful," he said. "Seeing a scene unfold from afar and anticipating something bad or good is what drives the drama." A dense rainforest or similarly crowded landscape would obscure the action, while a flat, barren plane would be too predictable. But the landscape in the film (and in the savannah) is just right. Under these conditions, "basically every move becomes a chess move," MacIver said – and is therefore far more entertaining to watch.
Not bulletproof yet
MacIver is the first to admit that more work is needed to make his hypothesis "fully bulletproof" – especially as it relates to the nearly four-fold increase in brain size that occurred with hominids after chimpanzee deviations. But his simulations "give a strong signal as to why land animals have become" smart "and water animals have not," he said. (A possible exception is cephalopods, which show signs of higher intelligence, possibly because, according to MacIver, they were hunted by land animals.)
He is currently working with Dan Dombeck from the northwest on a follow-up study in which he tests his computational predictions using experiments in robot environments. "We created this complex space with repositioning obstacles and controllable entropy, in which there are two robots," said MacIver. "One is a predatory robot that is powered by the same super-simple algorithm that was described in our article. For example, when it sees the prey, it runs towards it. The other robot is the prey." The prey has to reach the target because the predator is hunting just like in the online game.
More speculatively, MacIver believes that this could be relevant to the question of why people have so much trouble thinking about threatening existential threats, especially those in the distant future – such as climate change or antibiotic-resistant bacteria (or a global pandemic). "Since you believe that the ability to think about the future was driven by a need for planning and that our ability to think about the past is derived from that need, much of us may depend on why we developed the cycle to plan in the first place, "he said. "The reason why we're so bad planning for the far future can lead to restrictions in this circuit that we haven't yet developed cultural bypass technology."
DOI: Nature Communications, 2020. 10.1038 / s41467-020-16102-1 (About DOIs).
Listing image from YouTube / Northwestern University