Article 139 - A Potential Evolution of Human Brain Size

A Potential Evolution of Human Brain Size

This essay examines the evolution of human brain size in relation to human species, brain volume, potential neurons, climate and time.

The ratio of these are then examined.

The potential influence of current climate change on human brain size is then extrapolated.

Historic Data

Species Sahelanthropus

Brain volume (ml) 320 to 380 ml

Potential Neurons 22,222,222,080

Climate Miocene

18 deg c temperature

Time 21 to 14 million years ago

Species Australopithecines

Brain volume (ml) 380 to 430 ml

Potential Neurons 26,388,888,720

Climate Pliocene to Pleistocene

19 deg c to 6 deg c

Time 5 to 1.8 million years ago

Species Homo Habilis

Brain volume (ml) 618 ml

Potential Neurons 42,916,666,392

Climate Pleistocene

11 deg c

Time 2.8 million years ago

Species Homo Erectus

Brain volume (ml) 850 ml

Potential Neurons 59,027,777,400

Climate Pleistocene

11 deg c

Time 1.9 million years ago

Species Homo Heidelbergensis

Brain volume (ml) 1100 to 1400 ml

Potential Neurons 76,388,888,400

Climate Pleistocene to present

11 deg c to 16 deg c

Time 600,000 to 400,000 years ago

Species Homo Neanderthalensis

Brain volume (ml) 1600 ml

Potential Neurons 111,111,110,400

Climate Pleistocene to present

11 deg c to 16 deg c

Time 300,000 to 28,000 years ago

Species Homo Denisovans

Brain volume (ml) 1200 to 1400 ml

Potential Neurons 83,333,332,800

Climate Pleistocene to present

11 deg c to 16 deg c

Time 250,000 to 40,000 years ago

Species Homo Floriensis

Brain volume (ml) 380 ml

Potential Neurons 26,388,888,720

Climate Pleistocene to present

11 deg c to 16 deg c

Time 94,000 to 12,000 years ago

Species Homo Sapiens

Brain volume (ml) 1440 ml

Potential Neurons 86,000,000,000 to 100,000,000,000.

1 ml to 69,444,444 neurons

Climate Pleistocene to present

11 deg c to 16 deg c

Time 195,000 years ago to current time

Ratios of Data

Total evolutionary time

= 21,000,000 years

Smallest brain size to largest brain size

= 320 ml to 1600 ml

= 1 to 5 ratio

Smallest brain size to current brain size

= 320 ml to 1440 ml

= 1 to 4.5 ratio

Largest brain size to current brain size

= 1600 ml to 1440 ml

= 1 to 0.9 ratio (decrease in size)

Brain size evolution ratio

= 320 ml to 380 ml

= 380 ml to 618 ml

= 618 ml to 850 ml

= 850 ml to 1100 ml

= 1100 ml to 1600 ml

= 1600 ml to 1200 ml Denisovan decrease

= 1200 ml to 380 ml Floriensis decrease

= 1600 ml to 1440 ml Neanderthalensis to Sapiens decrease

Potential brain neuron evolution ratio

= 22,222,222,080 to 26,388,888,720 = 1 to 1.2

= 26,388,888,720 to 42,916,666,392 = 1 to 1.6

= 42,916,666,392 to 59,027,777,400 = 1 to 1.4

= 59,027,777,400 to 76,388,888,400 = 1 to 1.3

= 76,388,888,400 to 111,111,110,400 = 1 to 1.5

= 111,111,110,400 to 83,333,332,800 = 1 to 0.75 Denisovan decrease

= 83,333,332,800 to 26,388,888,720 = 1 to 0.3 Floriensis decrease

= 111,111,110,400 to 100,000,000 = 1.1 to 1 Neanderthalensis to Sapiens decrease

Brain size evolutionary time periods

= 21,000,000 to 5,000,000 = 16,000,000 years

= 5,000,000 to 2,800,000 = 2,200,000 years

= 2,800,000 to 1,900,000 = 900,000 years

= 1,900,000 to 600,000 = 1,300,000 years

= 600,000 to 300,000 = 300,000 years

= 300,000 to 250,000 = 50,000 years

= 250,000 to 94,000 = 156,000 years

= 250,000 to 195,000 = 55,000 years

Temperature range changes

= 18 deg c to 6 deg c = 12 deg c decrease

= 6 deg c to 11 deg c = 5 deg c increase

= 11 deg c to 11 deg c = stability

= 11 deg c to 16 deg c = 5 deg c increase

= 11 deg c to 16 deg c = 5 deg c increase but stable from last epoch

Combined brain size evolutions with potential brain neuron evolution ratio with brain size evolutionary time periods with temperature range.

= 320 ml to 380 ml : 1 to 1.2 : 16,000,000 years : 12 deg c decrease

= 380 ml to 618 ml : 1 to 1.6 : 2,200,000 years : 5 deg c increase

= 618 ml to 850 ml : 1 to 1.4 : 900,000 years : stability

= 850 ml to 1100 ml : 1 to 1.3 : 1,300,000 years : 5 deg c increase

= 1100 ml to 1600 ml : 1 to 1.5 : 300,000 years : stability

= 1600 ml to 1200 ml Denisovan decrease : 1 to 0.75 : 50,000 years : stability

= 1200 ml to 380 ml Floriensis decrease : 1 to 0.3 : 156,000 years : stability

= 1600 ml to 1440 ml Neanderthalensis to Sapiens 1.1 to 1 : 55,000 years : stability

Conclusions

The largest decrease in temperature over the longest time periods coincides with an increase in brain size.

The smallest increase in temperature over the second longest time period coincides with the largest increase in brain size.

Stable temperature conditions coincide with brain size increases to a lesser extent than they coincide with brain size reductions.

Therefore temperature changes coincide with changes to the brain size.

Therefore stable temperatures coincide on the whole to a reduction in brain size.

The current climate projections are for an unprecedented 2 to 6 deg c increase in global temperatures over the next 100 years.

Climate change from the data available could vary the human brain size due to environmental adaptation.

Sources:

http://en.wikipedia.org/wiki/Human_evolution

http://en.wikipedia.org/wiki/Australopithecus_afarensis

http://en.wikipedia.org/wiki/Paleocene%E2%80%93Eocene_Thermal_Maximum

http://en.wikipedia.org/wiki/Pliocene_climate

http://en.wikipedia.org/wiki/Plio-Pleistocene

https://www.google.co.uk/#safe=strict&q=earth%20temperature

http://www.livescience.com/40311-pleistocene-epoch.html

http://www.bbc.co.uk/nature/history_of_the_earth/Pleistocene

http://en.wikipedia.org/wiki/Homo_habilis

http://en.wikipedia.org/wiki/Homo_erectus

http://en.wikipedia.org/wiki/Homo_heidelbergensis

http://en.wikipedia.org/wiki/Neanderthal

https://abagond.wordpress.com/2013/07/26/denisovans/

http://en.wikipedia.org/wiki/Homo_floresiensis

http://en.wikipedia.org/wiki/Human

Ian K Whittaker

Websites:

https://sites.google.com/site/architecturearticles

Email: iankwhittaker@gmail.com

20/04/2015

14/10/2020

998 words over 4 pages