Is the Human Species Unique?
Impulse control may be the standout trait
What makes homo sapiens different? That is an old question, as we humans have become obsessed with believing ourselves unalike all else that now exists and has come before. In some ways, the answers have narrowed over time. With further study, much of what was thought as special and limited to humans has increasingly been found in other species. As the name describes, we are supposedly the thinking ape. But that is a bit vague. Thinking isn’t exactly uncommon, as all that is required is a brain. Even “higher” thinking is found elsewhere. Diverse animals will use complex search patterns such as recursion. Or more obviously, bees can do mathematical calculations. Various other species have been studied when problem-solving. Self-awareness has also been demonstrated by putting spots on an animal’s forehead and giving them access to a mirror.
Plus, many social species are playful, creative, engage in non-procreative sexuality, make and use tools, pass on cultural knowledge, learn social behavior, etc. (Murray Bookchin, Second Nature); although, interestingly, humans are more precise in learning through exact mimicry.
Evidence now shows that Neanderthals were making art before us, as other hominids made tools and used fire before us. In fact, humans didn’t become innovative until after sexually and possibly socially mixing it up with Neanderthals in the Levant. Even communication can be found outside of humans, if it’s not clear whether other species have full linguistic capacity. Prairie dogs, for example, develop immense numbers of names for other animals, going so far as to naming individuals who are regularly seen. The jury is still out on such things as whale songs that might be actual language, whether or not we’ll ever figure out how to translate them.
A point Robert Sapolsky makes, in his book Behave, is about the ability to delay gratification, how humans are able to “keep those dopamine levels up for decades and decades waiting for the reward.” He claims that it’s a trait not found in other animals, or at least not to the same extent. See Exploring Human Behavior: A Deep Dive into “Behave” by Robert Sapolsky by .
Is that true? It makes one wonder how delayed gratification could be meaningfully and comparatively defined, observed, and measured across species. Obviously, animals have all kinds of delayed behavior. But delayed gratification indicates a specific subjective state, condition, motivation, and intention. It would require the individual animal to perceive a possible gratification, desire it intensely enough to elicit potential (re)action, and then consciously engage some form of neurocognitive mechanism that suppressed and prevented the behavioral impulse to fulfill that gratification. Determining that seems beyond present capacities of scientific research.
A point Robert Sapolsky makes, in his book Behave, is about the ability to delay gratification … He claims that it’s a trait not found in other animals, or at least not to the same extent. Is that true?
For argument’s sake, let’s assume Sapolsky is correct. Besides the role of dopamine, his reasoning has to do with humans having a larger prefrontal cortex (PFC), specifically in terms of impulse control* and long-term thinking (Kori D. Miller, Don’t eat that marshmallow!), which admittedly is an area impressively advanced for humans. As the PFC is measurable in brain scans, that is partly the basis for the comparison he is making between species. We could think of other physiological mechanisms as well that would overlap with and reinforce this particular neurocognitive explanation. Impulse control coincides with greater neurocognitive development and functioning in general. So, this requires greater health to make that possible; such as with overall increased human brain size that evolved with earlier access to the nutrient-density of blubbery megafauna and seafood. That is why some describe humans as the hunting ape.
The PFC is also highly sensitive to reduction in glucose availability, a contributor to neurocognitive decline; particularly with metabolic syndrome, typically caused by excessive and chronic dietary intake of carbohydrates. Glucose, however, isn’t the only energy source for the brain. There are also ketones. This brings us to ketosis, the physiological state of higher ketone production achieved by restriction of carbohydrates or food in general. Though ketosis has long been part of evolution, humans have an atypical greater ability to go into ketosis easily and quickly. This means that not only can humans fast for long periods — with extra body fat, easily for weeks or longer — but, with increased ketone production, the human brain operates on a higher level while in ketosis and so this may have helped with improved neurocognition. Human neurons do love ketones and, when available, preferentially consume them in high amounts. Ketones also improve neurocognitive health (reduce epileptic seizures, improve depression, etc). But all of the body (muscles, heart, etc.) will use ketones.
Ketones are produced from fat, either body fat or dietary fat. Interestingly, while burning fat, the body can also endogenously produce water as a byproduct. The typical human can, without great risk, fast for a week or so without food and water; assuming they aren’t additionally under other kinds of stress (heat, hard labor, etc). So, fasting is one of the greatest talents of humans, and ketones allow us to remain physically active at high levels. Many tribal foragers hunt while in a fasted state. That would’ve been useful in the Paleolithic era when long periods, days to weeks, could pass in between megafauna kills and hence meals. Human evolution seems to have favored ketosis as a regular physiological state that is highly advantageous, related to why we put on body fat so easily for energy storage. The nutritionist Mary Ruddick found that at least some tribal foragers are often in a state of low level ketosis.
Though ketosis has long been part of evolution, humans have an atypical greater ability to go into ketosis easily and quickly … this may have helped with improved neurocognition
It’s common for traditional societies of all kinds to fast, sometimes for no particular reason. But fasting is often combined with other harsh, difficult, intense, and lengthy practices requiring self-control, focus, vigilance, or endurance: tests of courage, rites of passage, prayer, meditation, vision quests, trance states, ecstatic dancing, etc. In these societies, it can be a point of pride to be able to go without food, as it demonstrates one’s physical fitness or even moral character. It might be noted that, when in ketosis, hunger pangs reduce or entirely disappear. Many find, while on a keto diet, they lose food cravings, along with experiencing a reduction in other addictive tendencies, closely related to impulsivity.
To bring it back to Sapolsky’s view of human nature, ketosis strengthens impulse control and hence likely helps with delayed gratification as well. Commonly, keto dieters will speak of feeling different, what is sometimes referred to as keto calm or keto Zen. Along with improved energy and endurance, there is often greater alertness, clarity, focus, relaxation, reduction of anxiety, and general mood improvement (see Reddit discussions: 1, 2, 3, 4, 5, 6, 7, & 8). One person specifically noted a “significant reduction in impulsivity and restlessnes” (comment by Psyksess, A strange keto side-effect). For some, they’re so chill they’re not sure how to motivate themselves without the stress and anxiety that drove them previously. Then again, hyper-productivity wasn’t important for humans prior to modernity.
There are scientific explanations for why this might be the case and the keto diet has been well researched for more than a century. Some of the improvements would simply be reversal of metabolic syndrome and the balancing of blood sugar levels. And there would be improved mitochondrial functioning (Chris Palmer, Brain Energy). But in line with Sapolsky’s focus, as indicated by research, ketones affect the dopaminergic system, upregulate dopamine release, and raise the level of dopamine circulating in the blood (M. Dahlin, et al, CSF levels of dopamine and serotonin, but not norepinephrine, metabolites are influenced by the ketogenic diet in children with epilepsy; W.H. Church, et al, Ketogenic diet alters dopaminergic activity in the mouse cortex; V.R. Mahajan, et al, Ketone ester–enriched diet ameliorates motor and dopamine release deficits in MitoPark mice; & C. Poffé, et al, Exogenous ketosis increases circulating dopamine concentration and maintains mental alertness in ultra-endurance exercise).
To clarify a point that Sapolsky acknowledges, impulse control is not equally generalizable to all humans. It’s specifically and especially unique to healthy humans under the optimal conditions of evolutionary norms; not always seen in civilization, from the health decline of the agricultural revolution to modern shit life syndrome. Chronic stressors like malnourishment, lead toxicity, high parasite load, poverty, abuse, and such can severely stunt PFC development and hence compromise impulse control, as seen with higher rates of violent crime and other risky behaviors that, under sub-optimal conditions, coincide with the impulsive fast life history strategy (procreate early and often, then die young).
About malnourishment, research indicates that metabolic disorder, usually caused by a high-carb diet, is correlated to conditions involving impulsivity problems (e.g., ADHD); and correlated to mental illness and antisocial behavior, including impulsivity. Diet and nutrition is central (Mark Hyman, Food Fix; Georgia Ede, Change Your Diet, Change Your Mind; Weston A. Price, Nutrition and Physical Degeneration; and Mary Ruddick, see Youtube channel).
As a tool-wielding and hunting ape, one of the most important features is our opposable thumbs, but we’re not the only species to have them, even if we use them to greater effect. That has to do with a special talent for dexterity and hand-eye coordination, linked to intelligence and the PFC, with mental control (plus emotional self-regulation and self-soothing), including impulse control, as inseparable from physical control. As already noted, procuring meat and fat, along with breaking open bones to get marrow, allowed for more nutrition and calories to feed a larger brain and support ketosis. On a related note, humans have a down-turned nose. Some think this is to aid swimming by keeping water out of the nasal passage. It could relate to humans being hairless, such as why other water mammals sometimes lose their hair. Along those lines, being able to swim increased fish, cockles, and mussels in the human diet. It’s been argued that brain enlargement had much to do with the nutrients in these foods, specifically omega-3s. As a benefit, omega-3s are metabolized more quickly to form ketones.
When Paleolithic humans hunted megafauna, the whole community, men and women, would repeatedly jab the massive animal until it collapsed. Rather than individual strength, it was being able to cooperate, organize, plan, and coordinate that ensured survival.
By the way, a larger brain coincides with other changes, as the brain is an expensive powerhouse. More energy went to the brain instead of the intestinal tract, with the latter having shrunk as compared to the large guts of great apes (expensive tissue hypothesis). That meant humans lost the capacity to easily digest fiber, an energy-intensive process. Instead, we’ve come to rely on caloric-dense and nutrient-dense animal foods, along with easily digested fruit and nuts when in season.
Brain size may have also come at a sacrifice of muscle strength, as we are weak compared to closely related primates. With tool use, humans no longer needed to rely on brute force for defense and predation. In fact, one of the favorite early tools was the spear, which could be wielded by anyone. When Paleolithic humans hunted megafauna, the whole community, men and women, would repeatedly jab the massive animal until it collapsed (the reason why gender specialization of work didn’t increase until the megafauna die-off). Rather than individual strength, it was being able to cooperate, organize, plan, and coordinate that ensured survival. Plus, fine muscle control was more important for tool making and tool use.
The other related theory is that muscle strength was exchanged for endurance. That relates to ketosis. Humans have an immense capacity for extended physical activity without stopping or eating. And as already stated, ketones help with brain health and functioning. So, ketosis would improve maintaining impulse control for longer durations and under greater stress, such as suppressing hunger signals and maintaining hypervigilant focus while hunting for hours or longer. Many other human attributes would aid in such activities. Being hairless also helps with sweating to keep us cool while physically active in the heat. Another interesting feature is that human breathing can be out of sync with our gait. This allows us to slow down our breathing while running, which is necessary for endurance.
Though slow, humans are among the best long-distance runners in the animal kingdom. That is why we’re also called homo cursus, the running ape. Being able to continuously maintain a running pace was helpful for persistence hunting that is still done by some forager tribes.
The nutritionist Mary Ruddick went on persistence hunts with the Hadza and so made firsthand observations. They’d do so during the hottest part of the day, as the strategy is to force an animal into heat exhaustion. While tracking down their prey, the Hadza hunters wouldn’t carry or stop for food and water. When they passed a beehive, they wouldn’t bother to get any honey, even though it’s an occasional treat they enjoy (besides, honey is only available during 2–3 month wet season). They would completely focus on obtaining meat and this required amazing tracking skills, often done at a fast pace. It might take much of the day to run a large animal down. Even once the hunt was completed, they’d have to dismember and haul the carcass back to camp. So, that would be an example of impulse control and delayed gratification.
The nutrient-density of meat was worth it. To support this aspect, one visitor to the Hadza asked them, “What is the most important thing in life?” The top answer was meat. For foragers, most activity revolves around obtaining and preparing food, and often involving impressively complex processes (Sally Fallon Morrell, Nourishing Diets), as they really have little else that has to be done for survival. That brings us to another detail that stands out. For most apes ingesting a high-fiber diet, they have to be eating all day long. It’s time consuming to get energy and nutrition from fibrous plants. Whereas animal foods take less time, effort, and energy to obtain, consume, and digest. What this means is that humans, in their natural state, have a rather relaxed lifestyle. Research has found foragers only work 1–4 hours a day (Marshall Sahlins, The Original Affluent Society).
This leaves lots of extra time for socializing, conversation, debate, organizing, cultural activities, creativity, and making things. Combined with our great neurocognitive capacity, including impulse control, this made possible high levels of adaptability and innovation …
This leaves lots of extra time for socializing, conversation, debate, organizing, cultural activities, creativity, and making things. Combined with our great neurocognitive capacity, including impulse control, this made possible high levels of adaptability and innovation, along with skills of observation, analysis, speculation, experimentation, and long-term planning. This is seen with the immense knowledge and mnemonic systems that oral cultures develop and maintain (Lynne Kelly, Knowledge and Power in Prehistoric Societies; The Memory Code; & The Knowledge Gene), sometimes carrying knowledge across millennia (e.g., memory of the landscape under water that was last seen by humans during the Ice Age). More impulsive species never approach such impressive achievements. We humans can delay gratification not only over a lifetime but over multiple generations.
*More on impulse control
As a side note, impulse control is not to be conflated with egoic self-control as willpower, at least not as free will. Robert Sapolsky wrote an entire book, Determined, making a compelling scientific, philosophical, and moral argument for determinism; not to be confused with predictable, unchangeable, and hopeless fatalism. Like prosocial behavior, impulse control is simply an evolved trait of human nature; as it doesn’t require an agentic ego in the gaps or, as Sapolsky puts it, it doesn’t justify the claim of a floating turtle at the bottom of the stack (no magical causeless cause) — rather, it’s turtles all the way down. Simply put, there are neurological mechanisms that are able to intervene in other neurological mechanisms. But this process can be entirely explained in physiological terms, according to scientific knowledge.
Impulse control is as much part of human instinct as a hunger or pain response. It may make humans unique, but it doesn’t place us above scientific laws and the natural world. Impulse control, for example, can’t suppress gravity. In the context of what’s being discussed in this piece, we can ignore the free will versus determinism debate. Besides, one might argue that the entire frame of that debate is wrong or unhelpful. Whether or not agency exists, the isolated, autonomous, and hyper-individualistic ego theory of self might itself be incorrect. Even Sapolsky recognizes humans have the capacity for change, if it’s not through disconnected self-control. One could, instead, argue for an agency that is communal, as humans are a social species. That would be based on the bundle theory of self and 5E cognition (embodied, embedded, enacted, extended, & ecological); also see dividualism (Wikiversity, Social Relations as Persons; Ryan Salisbury, On Dividualism; & Jonathan Morgan, Societies Within).
Still, that is irrelevant to our purpose here. No matter one’s position on egoic self-determination and self-control, there is no reason to fear humans running amok; as Sapolsky also discusses. Impulse control, for humans in a natural state, is a natural instinct, not something needing to be imposed on reality. This relates to our social nature, as we automatically express prosocial behavior, at least when healthy and unstressed (Social Science As Intellectual Self-Defense; We Need To Talk About Health; & Sick Individuals = Authoritarian Societies). So, if we want to promote a better society, we might seek a better — more effective and compassionate — strategy than judging, shaming, blaming, and scapegoating individuals. The conditions that determine prosociality are collective and environmental, and therefore the importance of public health.
Impulse control, for humans in a natural state, is a natural instinct; not something needing to be imposed on reality. This relates to our social nature, as we automatically express prosocial behavior, at least when healthy and unstressed.
So, even if we want to believe in free will, we would be well advised to use our agency to improve shared conditions. Our greatest leverage for positive change is through a relational and communal identity (Gregory Boyd, Cherished Belonging). That would be the moral and rational course of responsible action. Free will or not, maybe we should seek to develop greater impulse control to suppress our judgmental and vengeful urges. The same reasons for impulsivity, antisociality, and punitiveness are the factors that cause stress, sickliness, and compromise; specifically harm to the highly sensitive PFC. For those who have been more fortunate in their life conditions, it’s not that they are morally superior and have greater heroic willpower. No. As Sapolsky concludes in analyzing the evidence, the moral impulse is a state of grace, requiring no effort at all. That state of grace is human nature at its best.
For further reading
- Ketogenic diet: a potential adjunctive treatment for substance use disorders
Deshenyue Kong, et al
“By analyzing data from 17 countries worldwide, sugar and sweetener supply quantity were significantly and positively associated with anxiety disorders, mood disorders, impulse control disorders, and SUD [substance use disorders]”
“standardised neuropsychological assessment […] indicated significant improvements in attention, abstract conceptual reasoning, and impulse control […] Subjective parent-, teacher-, and self-report questionnaire data […] indicated significant improvements in overall executive functioning, inattention, hyperactivity/impulsivity for all raters”
- A Ketogenic Diet Improves Cognition and Has Biochemical Effects in Prefrontal Cortex That Are Dissociable From Hippocampus
Abbi R. Hernandez, et al
“One mechanism for decline that the PFC and HPC share, however, is a reduced ability to utilize glucose for energy metabolism. […] [ketogenic diet]-fed rats had biochemical alterations within PFC that were dissociable from previous results in the HPC [hippocampus]”
- Acutely increased β-hydroxybutyrate plays a role in the prefrontal cortex to escape stressful conditions during the acute stress response
Hyeonwi Son, et al
“Our results suggest that the metabolism of BHB from peripheral blood in the PFC may contribute to acute stress responses to escape stressful conditions.”
“Studies show that individuals with ADHD often have reduced glucose metabolism in the prefrontal cortex, the brain region responsible for attention and impulse control.”
