Brains are pretty good. With a brain, you can sense and experience the world around you,
think, feel, learn and remember new things. But ultimately what brains and nervous systems
seem to be there for, is to help coordinate the interactions between cells, so they can
move and behave in unison. Humans brains can consider lights, sounds,
little chemicals floating in the air, the taste of food and how things feel from our
sensory cells, then tell our muscle cells to behave in a synchronized fashion to do
something beneficial based on it all. Our nervous system send and receive signals
in 2 main ways. Through neuron signals and hormone signals.
Neurons are cells that send and relay action potentials as signals. Signal comes in one
end, goes to other end and can connect to another neuron that does the same. In this
way they form a network all over your body that centralizes around your brain. This type
of signal is how your senses send signals to the brain and how motor functions are signalled
from the brain. There's lots of different neurons that do
different tasks and the brain itself operates with neurons. There's other kinds of cells
in there too. Some feed and regulate neurons, others sheath neurons making them go faster,
and others fight off bacteria and viruses and do cleanup. But your neurons and how and
why they connect is really where the fun happens. Hormones are chemicals that signal responses
in the body. So some cells can excrete a hormone, and then other cells have receptor proteins
that a hormone can bind to and initiate some response, like the production of a protein.
While neuron signals are much more precise, hormones can enter the blood stream and effect
everywhere, depending on what cells have the receptor. They generally have slower effects
than nerve signals and can signal things like mood and growth.
So with hormones and neuron signals, cells can grow and divide together, they can sense
and move together, and otherwise just behave in coordinated ways.
You can start classifying behaviours. Are they learned, like learning to use utensils
or learning to read. Are they more intrinsic, like sea turtles instinctively knowing to
head toward the light of the sea at birth. Are they uncontrollable and involuntary like
your heart beat. Are they voluntary like waving your arms around. Or a mix, like breathing.
Or maybe they're a reflex arc, that doesn't travel through the brain at all.
But how and why did these behaviours come to be? Why did brains evolve? Well, brains
evolved for the same reason everything else did. The genes that make neurons, hormones,
hormone receptors and everything else that influences behaviour, didn't come to be for
any reason but for the reproduction of those genes.
While this isn't the only thing that defines that behaviours are like. Because these elements
that facilitate behaviour are coded for by DNA that needs to reproduce to continue, some
of the behaviours they facilitate can seem pretty harshly self interested.
Like black headed gulls who nest out close to one another, will eat the babies of their
neighbors that aren't paying attention. Sounds brutal, but to them and their genes,
it's just another food source. And it's probably a lot easier than going fishing.
There's no such a thing as "for the good of the species" when we talk about why genes
and traits get passed down. It's all only for the reproduction of the genes.
So how can we explain non-selfish behaviours? I mean, just last week I saw a grown man ....not
eating someone else's baby. Why would he pass up such a defenceless meal. What's going on
there. I want to come back to the brains and neuroscience
stuff later maybe, this was just a short taste to introduce behaviour in terms of evolution.
In the mean time, watch the sides notes with why are girls crazy and a motion induced blindness
illusion to learn a little bit about how brains works. click here for the next video
...look at the red dot and pay attention to what happens to the yellow dots. The idea
is that the mechanisms between our eyes and our brains will ignore some visual information....
....so just by looking at which features are different on the males and the females, you
can sort of predict what their social structure might be like. So let's say there's a species
with the males that are bigger than the females, like with gorillas. What might you predict?
What are they using all those extra muscles for. If the males were always fighting for
mating rights....