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Why do we need less sleep than chimps?

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Sleep is so highly valued that it was at one time personified as a god/Jononmac46, CC

From BBC:

The theory goes that although we sleep for fewer hours than other primates, the sleep that we have is of high quality so we do not need as much.

To understand whether human sleep is unique, Samson and Nunn compared the sleep patterns of 21 primates, whose slumber patterns had already been analysed.

Humans therefore have the deepest sleep of any primate

As well as noting how long the animals slept for, they looked at how much time they spent in rapid-eye movement (REM) sleep. This is when we dream, and when our brain consolidates our memories into long-term storage.

Humans slept the least. The sleepiest primates were grey mouse lemurs and night monkeys, which slept for 15 and 17 hours respectively.

But in contrast, humans spent the highest proportion of their sleep in an REM state: almost 25%. “Humans therefore have the deepest sleep of any primate,” says Samson.

Other primates get much less REM sleep, between 5-10%.

Various factors are cited, like not sleeping in trees.

Regardless of why it happened, the fact remains that human sleep is strange compared to our closest living relatives. This suggests that we have evolved to need less of it.More.

Of course, spending more time in the type of slep that consolidates memories may well relate to a lifestyle that requires more learning.

See also: Human evolution, the skinny

and

Human origins: The war of trivial explanations

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Here’s the abstract:

Over the past four decades, scientists have made substantial progress in understanding the evolution of sleep patterns across the Tree of Life.[1, 2] Remarkably, the specifics of sleep along the human lineage have been slow to emerge. This is surprising, given our unique mental and behavioral capacity and the importance of sleep for individual cognitive performance.[3-5] One view is that our species’ sleep architecture is in accord with patterns documented in other mammals.[6] We promote an alternative view, that human sleep is highly derived relative to that of other primates. Based on new and existing evidence, we specifically propose that humans are more efficient in their sleep patterns than are other primates, and that human sleep is shorter, deeper, and exhibits a higher proportion of REM than expected. Thus, we propose the sleep intensity hypothesis: Early humans experienced selective pressure to fulfill sleep needs in the shortest time possible. Several factors likely served as selective pressures for more efficient sleep, including increased predation risk in terrestrial environments, threats from intergroup conflict, and benefits arising from increased social interaction. Less sleep would enable longer active periods in which to acquire and transmit new skills and knowledge, while deeper sleep may be critical for the consolidation of those skills, leading to enhanced cognitive abilities in early humans. (Public access) – Sleep intensity and the evolution of human cognition David R. Samson1,* andCharles L. Nunn2
Article first published online: 12 DEC 2015 DOI: 10.1002/evan.21464

3 Replies to “Why do we need less sleep than chimps?

  1. 1
    mahuna says:

    One should note that “primitive” humans, such as the Bushmen, spend FOUR (4) HOURS per day collecting and preparing food. Since they don’t have any other jobs, a HUGE portion of their day is spent TALKING.

    So, the “sleep bonus” that humans have over other primates was NOT used to collect more food or concoct better ways to kill the cousins on the other side of the hill. It was used to “chew the fat” with the rest of the man-pack, cuddle the precious babies and play with the toddlers, and stare up at the sky and envision Meanings for the cosmos. The other primates simply don’t bother about these things, so they might as well sleep their lives away.

    But again, humans appeared POOF! fully formed 1 million years ago and have been staring up at the same sky (and cuddling the same babies) ever since. There is no “evolving” involved.

  2. 2
    tjguy says:

    We might not agree on how long ago humans appeared, but we do agree that they appeared POOF! fully formed. Here is an article on creation.com that talks about an evolutionary exhibition in Britain about chimp-human evolution. It’s interesting.

    http://creation.com/image-of-god-or-ape

    Here is the pertinent part of the article:

    British Museum of Natural History exhibition stumped on evolution

    by Dominic Statham Published: 21 January 2016 (GMT+10)

    On 18th December 2015, the British Museum of Natural History (BMNH) opened their new ‘Human Evolution’ exhibition. A few days later, I travelled to London to take a look.

    It begins with the usual assertion of ‘the fact of evolution’ with a sign which reads, “The fossil record shows that the human family tree is made up of many ancient relatives, and that ape-like ancestors evolved into us.” Most significantly, however, it goes on to say, “Exactly who our direct ancestors were within this family tree is a subject of scientific debate”, and this admission is reflected throughout the exhibition. Speaking of the first display, museum palaeontologist Professor Chris Stringer commented,

    Well, we’ve attempted here to represent about 7 million years of human evolution on one diagram and you’ll notice a lot of skulls there with different species names … But you’ll notice also, unlike many of these depictions, we haven’t joined them up with lines of ancestors and descendents and that’s a reflection of the uncertainty about how these forms are related …1

    Also significant is that the chart contains just two main groups, one identified as ‘humans’ and other as ‘australopithecines’—with nothing bridging them.

    In other words, despite there being “a lot” of different species, he had found it impossible to put them in an order showing a clear evolutionary progression from ape-like creatures to man.

    Also significant is that the chart contains just two main groups, one identified as ‘humans’ and other as ‘australopithecines’—with nothing bridging them. ‘Species’ such as Homo neanderthalensis (‘Neanderthal man’) and Homo erectus (‘Peking man’) are placed in the blue area and described as ‘humans’, with just one species, Homo sapiens, in the subgroup, ‘modern humans’. Species such as Australopithecus afarensis and Australopithecus africanus are placed in the orange area and described as ‘australopithecines’. Since ‘australopithecine’ means ‘southern ape’ one might reasonably conclude that all these different ‘species’ (collectively known as ‘hominins’)2 should be classified as either ‘apes’ or ‘humans’, with no clear examples of ‘ape-men’.
    Au-afarensis

    [Fig. 2. Hypothetical reconstruction of Australopithecus afarensis by St Louis Zoo, Missouri. Note the ‘whites’ in the eyes giving the creature a more human-like appearance and an impression of intelligence. Credit: Ivan Burgener.]

    Further inside the exhibition are reconstructions of the heads and faces of various ‘human species’—Homo sapiens, Homo erectus, Homo neanderthalensis, Homo antecessor, Homo heidelbergensis and Homo floresiensis (fig. 1). What is so striking, however, is their similarities rather than their differences. They are all, clearly, so very human. In contrast the fossil skulls of australopithecines are so clearly ape-like (figs 2 and 3). Again, where are the transitional forms linking australopithecines to humans? Towards the end of the exhibition there is a full reconstruction of a ‘Neanderthal man’, leaving no doubt that, despite all that’s been said about this ‘species’ in the past, the museum scientists understand him to be fully human (fig. 4).

    Given their difficulties identifying a plausible evolutionary progression, showing how australopithecines slowly turned into humans, how can evolutionists be so confident that this is what actually happened? The answer, I have come to see, has very little to do with science.

  3. 3
    Robert Byers says:

    I don’t sleep puts memories in big storage. I did originally think sleep was entirely for memory restoration abilities because I believe the mind is just a memory machine. So the mind or memory needs restoration. some researchers say its about memory too.
    Yet i question now. when we are so tired in the body wHY should ir make the memory more tired?
    so it suggests there is a juice/adrenaline that is being restored.
    Memory or juice?? Hmmm.

    The thing behind this is to help heal those with fatigue syndrome.
    An option is that if its juice the interference of it makes those who have this problem.
    so important to fix it.

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