There are many studies out there that compare the size of brains from one living thing to the next. What has been found is that the size of the brain for a human and a dolphin are almost the same. This is based on information that shows the evolution of the cetacean brain over a period of more than 47 million years!

Such studies have given experts information about the large size of the brain for toothed whales. Some of these species have abilities that have only previously been seen to exist in some of the Great Apes as well as humans. Now they have also been observed with some of the species of dolphins.

Brain of Pacific white-sided dolphin / Author: Tranletuha.

There are studies that show dolphins have the ability to recognize who they are when they see their reflection in a mirror. They are also able to communicate using symbol based programs and through concepts that are abstract in nature. Some researchers believe that the large size of their brain is what allows such intelligence to occur.

Yet what continues to be a huge mystery to the experts is the evolution of the brain over time. One of the largest fossil studies that has ever been conducted has been done by Lori Marino has several of her colleagues from Emory University in Atlanta. The study spanned 4 years looking over various collections in different museums.

The team used 66 different fossilized cetacean skulls that they found. Using CT scans, they were able to document the size of each of the brains. They were also able to document the body mass through the bones found at the base of each skull.

This study also included looking at similar data already collected on 144 cetacean skulls. This resulted in a total of 210 samples being looked at, with 62 species and 37 different families being represented in that total of samples. Find the EQ, or Encephalization Quotient, of each one was the purpose of collecting such data.

If you aren’t familiar with EQ, it is a representation of the ratio of brain to body mass. The scale works like this:

Large brain size – EQ greater than 1

Average brain size = EQ of 1

Smaller than average brain size = EQ less than 1

The largest of all creatures is humans with an EQ of 7. There have been two significant points in the evolution of cetacean that the EQ showed a significant jump. The first dates back about 35 million years ago. There were dramatic changes to the EQ as well as to changes in body size.

There are studies that indicate the development of larger brains was the result of the evolution for echolocation. This is the use of high frequency sounds that can be picked up as they echo off of various objects. Then the animals are able to interpret a variety of information from that occurrence.

It is believed the second dramatic increase in brain size occurred about 15 million years ago in the Delphinoidea super family. This includes narwhales, belugas, dolphins, and porpoises. The information from fossil records suggests that these increases were significantly more than that of humans or great apes.

The findings of this study are believed to be one of the few that have helped us to gather such information from the fossil records. Such research is time consuming but it is also very important as well as interesting. If you are interested in reading more about the research this team has done, it will be in The Anatomical Record, December issue.

Source: http://dsc.discovery.com/news/briefs/20041108/dolphin.html

– Dolphins are dying more frequently than ever before because of the consequence of human activities. Among them:

– They get caught in fishing net quite often. Usually, fishers are not targeting dolphins, but commercial species which are also the prey of dolphins. Gillnets, trawls, and longlines are some of the most dangerous fishing devices that trap and kill dolphins.

– Dolphins also die frequently because of the ocean pollution, either by poisoning or by eating drifting garbage.

– Other times these cetaceans die as result of beach strandings which some think are caused by noise pollution.

– Finally, some industries intentionally kill dolphins for commercial purposes. While protected in most parts of the world, some countries invoke their ancestral customs to kill an insulting number of dolphins every year.

Besides the common predators like big sharks and occasionally killer whales, humans are the top killers of dolphin. If dolphins could figure it out, we would be considered their worst enemy.

The human activities that kill dolphins are fishing because dolphins get trapped in the nets while they try to catch tuna or some other species.

Also, human pollution is a huge threat for dolphins causing them to choke by eating debris or by damaging their senses and making them easy prey for sharks.

The excessive noise product of human activities in the ocean is also a threat to dolphins, as noise can kill dolphins or at least confuse them causing massive beach stranding.

Dolphins have helped people in many ways, and there is a large number of stories about dolphins helping people since the ancient Greece.

Sometimes, dolphins have helped humans in the ocean by protecting them from shark attacks which are usually done swimming around the person and making sharks go away.

Other anecdotes relate how boats avoided wreckage by following dolphins during thick fog conditions until they managed to pass through dangerous waters.