![dolphin brain dolphin brain](https://i.pinimg.com/originals/52/01/22/520122a58a6dbed8469c57bcae75dfa7.png)
Tied to this, it has generally been thought that baleen whales had small brains compared to toothed whales (the group that includes sperm whales and dolphins) because they did not echolocate. Dolphins have evolved surprisingly big brains over the last 47 million years, according to the largest fossil study ever done on the animals. 'This is surprising because dolphins and bats.
![dolphin brain dolphin brain](http://1.bp.blogspot.com/-sufBjfMh2ag/U0Fdcf_1IvI/AAAAAAAAMYk/v4dT1jL16gs/s1600/Acquarium+--+shark+brain+vs.+dolphin.jpg)
The argument is that toothed whale brains evolved to be large in size (even relative to their body size) due to the need to process complex sensory information that is gathered during echolocation. That makes dolphin brains similar to those of bats something that is probably related to their use of echolocation to 'see' their environments. Dolphins and other toothed whales use a series of high-pitched clicking sounds, which are ‘beamed’ out through their heads and reflected back off objects such as prey. One of the most prevalent arguments is tied with echolocation a sense used to navigate environments and hunt prey 2. Despite the amount of scientific research undertaken in this area, the reason why this group evolved large brains remains abstract. Many species also have brains that are relatively large compared to their body size. The team think that humans and dolphins are near-uniquely susceptible to Alzheimer’s Disease because of alterations in how the hormone. Cetaceans (whales and dolphins) are renowned as having the largest and one of the most highly developed brains in the animal kingdom – for example, the sperm whale has a brain roughly 7-9 kg in size 1. The team analysed ‘plaques’ of a protein called beta amyloid in the brains of dolphins, as well as tangles of another protein called tau: these plaques and tangles are signatures of Alzheimer’s Disease.