dream-benno-meyer-rochow-science-biology

When we Dream…..

Do we then Become More Animal-like?

Sometime ago I attended an international conference in Finland on brain development and brain function. Apart from an excellent discussion on when, at what time of the development during foetal or post-foetal life, pain stimuli are registered and processed by the human brain, it was the session on dreaming that interested me most. Some of the more surprising pieces of information from the dream presentations I still remember and it is those that I shall now elaborate upon.

Everyone who owns a cat or a dog and has observed his or her pet when asleep, knows that not only humans dream. A sleeping dog may growl, snarl, kick with its legs, whimper or even urinate. A sleeping cat may swish its tail around for no apparent reason, flick its ears and smack its lips with its eyes closed. These animals dream and during their dream phases the eye balls behind their closed eyelids move rapidly, just as they do in a dreaming human. There are ways to record these “rapid eye movements” (which, for short, are termed REMs) and relate them to brain activity.

When humans are woken up immediately after an REM-phase, they can report a dream. But which part of the brain is the culprit? Where are the dreams produced or located? Electroencephalograms, called EEGs, provide part of the answer. The cortex is what we might call our ‘thinking cap’, where all our logical decisions during wakefulness are made, but it changes its functional characteristics like brain-wave frequency and amplitude completely during REM/dreams and therefore has to be involved. However, what is even more fascinating and was presented as a novel twist in the research on dream generations was that those brain areas we share with other mammals like dogs, cats and even lower vertebrates, namely the hind/brain, the cerebellum and the diencephalum, ─ areas of the brain in other words, in which reflex movements and automatic motor reactions are linked with instinctive behaviours, fear, flight, aggression, and desires ─ those areas of the brain are active, too!

Young mammals, in which the cerebral regions of the brain are not yet fully developed have more and longer REM/dreams than older animals. And, would you believe it, even in the human foetus REM-phases exist, which suggests that it already creates its own dreams unless, of course, the cerebellum only moves the eyeball without a proper dream. In adult dreamers, however, it is believed that sensory-motor memories and other tasks of the cerebellum are transferred to the cerebral cortex and in this way strongly influence the flavour of what and how we dream. What this suggests to me, if I understood the speaker correctly, is that during dreams, we take a giant time-leap back to our archaic, animalistic roots, to our beastly ancestors. It seems that in our dreams we are, indeed, more closely related to our four-legged friends than during hours of wakefulness. And that leaves me wondering now if I might have actually barked, meowed or perhaps even crowed like a rooster in my sleep sometimes.


meat mammoth paleo diet food cooking

Let’s get back to the roots !

© Dr V.B. Meyer-Rochow and http://www.bioforthebiobuff.wordpress.com, 2016.
Unauthorized use and/or duplication of this material without express and written permission from this site’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to V.B Meyer-Rochow and http://www.bioforthebiobuff.wordpress.com with appropriate and specific direction to the original content.

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Dr Meyer Rochow bio essay : "Hitching a ride"

Teeth

Something to chew on

Many years ago on a Caribbean Cruise I met a man who had made a fortune with artificial teeth or, to be more precise, with developing chemicals for colour nuances between snow white and yellowish brown. I learned from him that human teeth display hundreds of subtle hues and of course jacket crowns or dentures need to resemble the natural teeth of a person.

Teeth, as we all know, hold important clues for the criminologist, but also for the palaeontologist studying distribution and evolution of vertebrates. Teeth are extremely durable; they are useful for seizing and chewing food and consist of bonelike material called “dentine” capped with the even harder “enamel”. Teeth in mammals can be categorized as incisors (the front teeth), canines (the corner teeth), and molars (the grinding teeth further back), but dolphins seem to lack dental specializations. Apart from their biting and chewing function, teeth may have other roles to play. In humans speech without teeth becomes slurred and difficult to understand. Baring of the teeth has signal function not only in humans, but many species, e.g., dog, monkey, horse, etc. Teeth in mole rats are used as “digging tools” to excavate the subterranean tunnels these rodents live in and large visible teeth may be a sexual characteristic as, for example, in boars, musk deer etc. In the pig deer (Babyrousa babyrussa) of Sulawesi, canine tusks of the male actually grow upward through the flesh of the snout and, continuing to grow, may even penetrate the animal’s skull!

Teeth can also be formidable weapons in defence, even if useless for biting and chewing: the tusks of elephants and hippopotamuses come to mind. But while the up to 80 cm long and six kg heavy tusks of the hippos are anatomically canines, those of the elephant are incisors. Incidentally, the world’s first plastic (namely celluloid) was invented by John Hyatt in 1865 to protect elephants, whose tusks, i.e. the ivory, was used to manufacture billiard balls for the increasingly popular cue sports like snooker etc. Some of the most complicated teeth are not found in mammals, but in snakes and certain deep sea fishes. Some venomous serpents possess hollow teeth with a canal inside for injecting or spitting venom, while some deep-sea fish may sport hinged and dagger-like teeth of grotesque proportions. And talking about fishes, sharks actually carry teeth not only on their jaws but much smaller ones, yet nonetheless proper little teeth, all over their body. Birds do not normally have teeth, but very occasionally reports of birds with a couple of teeth have been published, which serves as a reminder that the birds’ ancestors were indeed reptiles – and they did have teeth.

Although most mammals have two generations of teeth (milk and adult teeth), the proverbially lazy sloth produces only one set. A single over one metre long tooth is the rule in the Arctic narwhale male and a few mammals like the Australian platypus and anteaters have no teeth at all when adult. However, how silly zoological nomenclature can sometimes be shows the example of the armadillos: classified as “Edentata” (toothless animals), they actually possess more teeth than many other mammalian species. And toothless humans? Well, they are being helped by my acquaintance from the Caribbean Cruise.

thirst ship sheep sailor evolution

Let’s embark on another ship with this story!


© Dr V.B. Meyer-Rochow and http://www.bioforthebiobuff.wordpress.com, 2016.
Unauthorized use and/or duplication of this material without express and written permission from this site’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to V.B Meyer-Rochow and http://www.bioforthebiobuff.wordpress.com with appropriate and specific direction to the original content.

fecundity competition reproduction

Fecundity Competition

How to be fecund : be fruitful and multiply

Sometimes when you read about the human population explosion you may think our own species’ fecundity must be enormous. However, even assuming an average life span of 65 years and an average number of children of four in a person’s life, our reproductive rate would not at all be high. Rodents are doing much better and have no trouble at all outperforming us.

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