The brain is one of the most complex organs in the human body. There have been many researches on this topic and today prof. Josh Martin brought us the exploration of the Origins of Brains.
He started the lecture with the interesting video to see the insects’ cognitive process. It gave us an idea that how a mantis recognizes a fly with his eyes and catches it with his hands. The mantis was moving smoothly using each bodies’ function effectively. Obviously it tells us that the brain of the insect has to be able to work in order to be successful of what it needs to do which is to catch the fly. As another example, I remembered the science lecture about the cognition in insects. One of the example was bumblebees. Recent experiment showed that once one bee figured out what it is necessary to do to access the reward, flower, other bees that were observing learned the string-tugging trick themselves. Furthermore it became part of the colony’s skillset, transmitted from bee to bee after the first string-pulling bee had died. In spite of the fact that bees have such a small brain, they are able to learn each other and take complex action beyond our expectation. Simultaneously when we look at the human activity, for example when we catch the ball flying towards us, it is a similar play or task the mantis does by positioning its body to be able to reach out the fly. Is there are any connections between we human beings’ brains and insects’?
The origin of brains goes back to 750 million years ago. Ediacaran Biota is considered the grand ancestor of all species. Since then many species had been branched out and took their own development by adjusting the environment they faced. So even we take an example of worms as a big category, their structure of neuron system varies depends on their genetic groups. In other words, some of their brains are close to related insects, and some are related to the group we human beings belong.
It is said that human’s adult brain is 1400 kg, the surface area is 2500 ㎤ and the number of neuron counts as 100 billion. Contrary insects, for instance a grasshopper, the brain width is less than 2mm, capacity is 6 mm3, and the number of neuron is considered as 400,000. There exists the two extremes of both big brains and small brains. However, it does not mean that human big brains developed from small ones of insects. As the chart of a phylogeny of brain which prof. Martin introduced clearly shows that the grand ancestor differentiated 500-600 million years ago into protostome which insects belong and deuterostome which human does and both took totally different paths in order to develop their own brains.
Since the brains of insects are small, they have relatively independent nerve system. They have various ganglia throughout its body to control most of the overt behaviors. Thus, even if you cut off the head of some insects, they can live for a while because the segmental ganglia still function independently. The human brain has an advantage of memory, information processing and information integration which enable us to learn complicate subjects, understand languages, do multi tasks, and to have long term memory.
It was interesting to look into the different developments in brains across different species starting from the same origin. Our origin story of brain evolution involves some of us moved forward, some of us died in that the way suits in each animals. Human and insects, in either case, we all have been making a spectacular progress and still we are.