Is it true that an ostrich's eye is larger than its brain?

There is an opinion that an ostrich's eye is larger than its brain, which allegedly explains the low intellectual abilities of this bird. We decided to check whether this opinion is supported by scientific research.

Usually the statement about such a relationship between the eye and the brain of an ostrich is found in jokes And demotivators. Also this information meets in collections of interesting facts, social networks, publications Media And TV programs. Some sites It is even claimed that the ostrich's brain is so small that it is only a quarter the size of its eye. About the fact that the ostrich is stupid, speaks even the biblical book of Job (39:14-17): “He leaves his eggs on the ground, and warms them in the sand, and forgets that his foot can crush them and the beast of the field can trample them; he is cruel to his children, as if they were not his own, and is not afraid that his work will be in vain; because God did not give him wisdom and did not give him meaning.”

Ostriches are the largest representatives of the class of birds. Yes, African ostrich reaches 2.7 m in height and can weigh up to 156 kg. Ostriches live in the eastern and northwestern parts of the African continent, but 8 million years ago their habitat captured vast territories: from modern China and Irkutsk to the southern regions of Ukraine and Moldova. Contrary to popular belief, the emus that live in Australia are not ostriches; they are representatives order of cassowaries. Interestingly, the scientific name of the ostrich (Strouthokamelos) is from Greek translated like a "sparrow camel".

Ostriches have really big eyes. Visual organs of this size are necessary in order, on the one hand, to look out for food, and on the other, to notice a potential threat in time. Moreover, the ostrich, like other birds, has more wide compared to human field of view. Each eye covers about 150–170°, with only 20–30% overlap between the left and right fields, giving a total of almost 300° of vision. 

The ostrich brain, like the brain of mammals, consists of of two hemispheres separated by a longitudinal fissure. The surface of the hemispheres is smooth, without convolutions.

The brain has diamond-shaped shape, so scientists use two dimensions to describe it: length and width. According to scientists from Huazhong Agricultural University (Wuhan, China), the brain is 59.26 mm in length and 42.30 mm in width, according to other sources - 58.48 mm and 42.63 mm, respectively. The ostrich's eye is spherical in shape with an axial length at 39 mm. A ball with a diameter of 39 mm is smaller than a diamond with the length and width indicated above.

Scientists estimate the weight of the ostrich brain to range from 26.34 g to 41.9 g. In academic sources, the weight of an ostrich eye could not be found, but others disagree: some claim that the weight reaches up to 60 g, in others it evaluate at 40 

At the same time, ostriches still cannot be called absolutely stupid animals. The brain even allows them to remember and carry out some commands, which makes them animals, capable to training. Moreover, ostriches use as riding animals, harnessed to a team or simply sitting on top of them, while neither saddles nor harnesses are used. Ostrich racing takes place start in South Africa, however, the most popular today in the southern United States. 

Thus, if we count by size, the ostrich's brain is, on average, still larger than its eye. However, the mass of this bird's eyes is most likely slightly larger than its brain.

Mostly not true

What do our verdicts mean?

Read on the topic:

1. Bird brains: what do we know about the intelligence of birds?
2. Birds have discovered consciousness and brain architecture similar to mammals