What is the Difference Between Humans and Animals Brain

The main difference between humans’ brain and animals’ brain is that humans’ brain has a remarkable cognitive capacity, which is a crowning achievement of evolution whereas animals’ brain shows comparatively less cognitive capacity. Furthermore, the cerebral cortex, which is responsible for the higher cognitive capacity of the human brain is disproportionately large, accounting for more than 80% of the total brain mass while the cerebral cortex of the animal brain is not significantly large.

Humans’ brain and animals’ brain are one of the two parts of the central nervous system responsible for thoughts, memory, and the movement of the body.

Key Areas Covered

1. Humans’ Brain
     – Definition, Structure, Significance
2. Animals’ Brain
     – Definition, Structure, Significance
3. What are the Similarities Between Humans’ and Animals’ Brain
     – Outline of Common Features
4. What is the Difference Between Humans’ and Animals’ Brain
     – Comparison of Key Differences

Key Terms

Animals’ Brain, Cerebral Cortex, Cerebrum, Cognitive Capacity, Humans’ Brain

What is Humans’ Brain

Humans’ brain is a part of the central nervous system located in the skull. The main function of the humans’ brain is to control the functions of the body by integrating, processing, and coordinating the information to make decisions and send them to the effector organs. It is comparatively large; the human brain weighs around 1.2 kg. The main parts of the human brain are the cerebrum, the brainstem, and the cerebellum. The largest part of the humans’ brain is the cerebrum, which contains two cerebral hemispheres. The core of the cerebrum contains white matter while the outer layer or the cerebral cortex contains gray matter. Furthermore, neocortex and the allocortex are the two parts of the cerebral cortex.

Figure 1: Human Brain

Moreover, each brain hemisphere is made up of four lobes: frontal, temporal, parietal, and occipital lobes. Here, the front lobe is associated with some executive functions including self-control, planning, reasoning, and abstract thought. On the other hand, the temporal lobe is responsible for visual memory, language comprehension, and emotion association. Parietal lobe is responsible for spatial sense and navigation while occipital lobe serves as the visual processing complex. Although the left and the right hemispheres are similar in size and shape, the left hemisphere is responsible for functions including language while the right hemisphere is responsible for visual-spatial abilities.

Moreover, the brainstem connects the cerebrum to the spinal cord. The midbrain, the pons, and the medulla oblongata are the major parts of the brainstem. However, pairs of tracts connect the cerebellum to the brainstem. Additionally, other important brain structures including the thalamus, epithalamus, pineal gland, hypothalamus, pituitary gland, and subthalamus occur underneath the cerebral cortex.

What is Animals’ Brain

Animal’s brain is also part of the central nervous system, occurring in the head region. Based on the structure, three types of animals’ brains can be identified. They are the invertebrate brain, vertebrates’ brain, and mammals’ brain. Invertebrates’ brain includes the brain of mollusks, arthropods, worms, and tardigrades. Among them, the most complex brains occur in arthropods and mollusks. They are made up of twin parallel nerve cords that extend through the body. The supraesophageal ganglion serves as the arthropod brain and the brains of mollusks are the largest.

Figure 2: Animal and Human Brain

Furthermore, the three main parts of the vertebrate brain are prosencephalon (forebrain), mesencephalon (midbrain), and rhombencephalon (hindbrain). The six parts of the vertebrates’ brain are the telencephalon (cerebral hemispheres), diencephalon (thalamus and hypothalamus), mesencephalon (midbrain), cerebellum, pons, and medulla oblongata. However, the main difference between vertebrates’ brain and mammals’ brain is the size. Also, the midbrain and the hindbrain of mammals are comparatively small while the forebrain is comparatively large. Humans’ and primates’ brain show massive expansion of the cerebral cortex, which in turns enhances their cognitive capacity.

Similarities Between Humans’ and Animals’ Brain

• Humans’ and animals’ brain are one of the two components of the central nervous system while the second component is the spinal cord.
• Both occur in the head region of the body.
• Besides, the brain of the vertebrate animals occurs inside the skull, a cover made up of bones.
• The brain of both is made up of neurons and supporting cells called neuroglia.
• Also, the main parts of the vertebrate brain are telencephalon, diencephalon, midbrain, cerebellum, pons, and medulla.
• Furthermore, the main function of both the brains is to control thoughts, memory, and the movement of the body.

Difference Between Humans’ and Animals’ Brain

Definition

Humans’ brain refers to the central organ of the human nervous system, consisting of the cerebrum, the brainstem, and the cerebellum, while animals’ brain refers to the organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals.

Relative Brain Size

However, a difference between humans’ and animals’ brain is that the humans have a three-times bigger relative brain size between body mass/weight and brain size while animals have a relatively small brain size.

Size of the Cerebral Cortex

Moreover, the size of the cerebral cortex is also a difference between humans’ and animals’ brain. Humans’ brain has a disproportionately large cerebral cortex, accounting for more than 80% of the total brain mass, while the cerebral cortex of the animals’ brain is comparatively small.

Number of Neurons in the Cerebral Cortex

Also, the humans’ brain contains around 16 billion neurons in the cerebral cortex while animals’ brain contains comparatively a lesser number of neurons in the cerebral cortex.

The thickness of the Cortex Layer

The thickness of the cortex layer of humans’ brain is high while the thickness of the cortex layer of the animal’s brain is low.

Wrinkles in the Cortex

Another difference between humans’ and animals’ brain is that the cortex of the humans’ brain is fully-wrinkled while the cortex of most of the animals’ brains is smooth.

Cognitive Capacity

Importantly, the cognitive capacity of the humans’ brain is high while the cognitive capacity of the animals’ brain is low. Thus, this is the main difference between humans’ and animals’ brain.

Supporting Brain Cells

Another difference between humans’ and animals’ brain is that humans’ brain has more glia while animals’ brain has comparatively less number of glia.

Neural Connectivity

Besides, humans’ brain has more-developed neural connections while animals’ brain has less-developed neural connections.

Intelligence

Intelligence is also a major difference between humans’ and animals’ brain. Humans are more intelligent due to their increased neural connections in the brain while animals are comparatively less intelligent due to fewer neural connections.

Neocortex

In addition, humans’ brain has the largest neocortex while the neocortex of animals’ brain is comparatively small.

Complex Processing

Humans’ brain has the ability of complex processing such as conscious thought, language, and self-awareness due to the presence of a large neocortex while animals’ brain has a less ability of complex processing.

Olfactory Bulb

The olfactory bulb of the humans’ brain is small; hence, humans have a less sense of smell. However, the olfactory bulb of the animals’ brain is comparatively large; therefore, animals have a comparatively high sense of smell. Hence, this is also a difference between humans’ and animals’ brain.

Infrared Sensitivity

Humans’ brain is not sensitive to the infrared region while some animals’ brain is sensitive to the infrared region.

Navigation

The natural navigation ability of humans is less-developed while some animals such as pigeons respond to the magnetic field to find the location.

Neurogenesis

Neurogenesis only occurs in the regions of the brain responsible for memory and sense of smell in both animals’ and mammals’ brain while neurogenesis occurs in all parts of the non-mammals’ brain.

Conclusion

Human’s brain is one of the two components of the central nervous system. Its relative size is three times bigger.  Humans’ brain produces a high cognitive capacity with complex processing including conscious thought, language, and self-awareness. On the other hand, animals’ brain is also a part of the central nervous system but, its relative size, the size of the cerebral cortex and the number of neurons in the cerebral cortex are low. Therefore, animals show less cognitive capacities. Thus, the main difference between humans’ and animals’ brain is cognitive capacity.

References:

1. Roth, Gerhard. “Convergent evolution of complex brains and high intelligence.” Philosophical transactions of the Royal Society of London. Series B, Biological sciences vol. 370,1684 (2015): 20150049. doi:10.1098/rstb.2015.0049

Image Courtesy:

1. “Figure 35 03 02b” By CNX OpenStax (CC BY 4.0) via Commons Wikimedia   
2. “Vertebrate-brain-regions small” By Looie496derivative work: Looie496 (talk) (Public Domain) via Commons Wikimedia