. . . e v o l u t i o n e m . . .

 

         taking a fresh look at evolution

 

Brain morphology - betrays level in the evolutionary tree

 

I will show brain morphologies of a wide range of mammals to illustrate their positions on the evolutionary tree. These coronal sections of mammal brains are courtesy of brainmuseum.org. Images on the brainmuseum web-site are from collections at the University of Wisconsin and Michigan State and also from the Museum of Health, Science and Medicine.

 

You will note from these comparisons that the aspect of most significance is the top area of the brain.

It can be seen that the successive layers have been added to the top part of the brain during different stages of evolution.

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Mammals such as the platypus, marsupials, rats, rabbits, lemurs etc. have only one layer. I will describe them as having a linear  arrangement or X1     

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Next come the  half cross arrangement or X2 of the hyrax and American badger: (Taxidea taxus)

 

 

 

 

 

 

 

 

 

 

 

 

Then the full cross arrangement or X3 of the mongoose, hyenas and many African monkeys:

Then the  ‘cross of lorraine’ arrangement or X4 of the canids, dolphins, apes and humans.

 

 

The following brain sections show the similarity between human brains and the chimpanzee. Gorillas and Orang-utans will no doubt be similar too - but images of coronal sections of these apes’ brains are not currently available. Surprisingly the canid brain (coyote Canis latrans) is the next closest configuration below the apes if one considers the ‘Cross of Lorraine‘ arrangement.

 

Recent work on mapping brain functions in humans indicates that memory is associated with the uppermost areas of the brain. See watching the brain in action web-site. This is the top area of the frontal lobe. Robert Lehr of www.neuroskills.com. describes how  the functions of the different areas of the brain  have been determined by studying cases of traumatic brain injury. This top layer of the frontal lobe is associated with a higher degree of ‘consciousness’ with our environment.

 

Homo Sapiens

 

 

Then we have  the Chimpanzee (Pan troglodites)

 

 

 

The coyote (Canis latrans) is very similar.

 

The Rhesus monkey (Macaca mulatta) is shown below left, while the Mangabey monkey  (Cercocebus torquatus) is shown below right.

 

                 

Both of these monkeys are perhaps derived from the hyenids. The hyena brain (Crocuta crocuta) is depicted below.

 

The American Badger seems to be intermediate between the hyrax and the hyena.

 

 

 

Then the hyrax (Procavia capensis)

 

 

 

 

 

The mongoose (Cynictus penicillata) is depicted below  and appears to come somewhere below the hyena.                                                                                                               

                                                   

   

 

Then the rabbit (Orytolagus cuniculus)

 

 

Then the dormouse (Glis glis)

 

 

Then the marsupial Caenolestid  (Lestoros inca)

 

Then the Platypus monotreme (Ornithorynchus anatinas)

 

 

 

 

 

If we look at the complexity of the dolphin brain, we can assume they are very intelligent.

 

Dolphins  (Tursiops truncatus) are limited by their mode of life and because they only have paddles and not hands they are unable to make tools etc. Accordingly their inherent intelligence cannot be fully exploited in the same way man has been able to exploit his.  

 

The harbour seal (Phoca vitulina) appears to be intermediate between a canid and the dolphin

 

 

The coyote canid is depicted again for comparison

From these images it is quite feasible that  the seal evolved from an intelligent canid species which had become dedicated to hunting for fish in rivers and estuaries.  The dolphin and all the toothed whales are a natural progression towards total dedication to the open sea, abandoning terrestrial contact altogether. The manatees and baleen whales may have evolved on a similar pathway but perhaps from an ungulate species and not a canid species. The manatee (Trichechus manatus) brain  section is considerably different :

 

 

 

OTHER  X3 BRAINS

 

The Flying Fox (Pteropus giganteus) above

 

 

The mongoose (Cynictus penicellata) depicted above

  

The Red Panda  (Ailurus fulgens) ((note similarity of hyena brain architecture)  also above.

 

The Red Fox (Vulpes vulpes) cross-section above shows that the red fox is not closely related to canids like the coyotes.

 

The Squirrel Monkey (Saimiri sciureus) above

 

The Rhesus Macaque (Macaca mulatta) above

 

The Polar Bear (Ursus maritimus) seems to have a intermediate brain architecture between the X3 and X4 brains.

 

 

A New Interpretation on the Evolutionary Tree

 

Features such as dental configuration and bone length or foot configurations etc. are variable structures and hence not reliable as criteria for grouping related species. Brain architecture, however, appears to be more consistent in its form - betraying  serial evolutionary processes rather than parallel ones.

By looking at brain architecture we can identify crossover continuity say between birds and monotremes, monotremes and marsupials and ultimately marsupials to true placentals. The brain of the marsupial Caenolestid  (Lestoros inca) is not far removed from the Platypus (Ornithorynchus anatinus) both of which can be seemed to be similar to the brain of the goose .

 

To me it elegantly indicates to us that apes are derived from intelligent canids and not from monkeys.