2.2: Scale, Human Space, Powers of Ten for Physical Anthropology

Anthropology is a broad field that incorporates many sub-fields and borrows from many other disciplines, so the space that is relevant to physical anthropology is also vast. It ranges from the atomic particle that causes genetic mutation—the primary cause of evolution—to the plasticity of the human body because of our need to adapt to seasonal changes caused by the elliptical orbit of the planet in the solar system. Anything bigger or smaller is beyond the scope of physical anthropology. Why atomic particles behave the way they do is a question of physics. Whether life exists on other planets is a question of astrobiology. Both are good themes for philosophy and science fiction, but are beyond the scope of this class.

Meters	Common Measurement	Abbreviation	Relevance
10 ^-10	1 ångström	1 Å	Size of an atom
10 ^-9	1 nanometer	1 nm	Diameter of DNA helix, size of a base
10 ^-8	10 nanometers	10 nm	Size of a codon (3 base pairs)
10 ^-7	100 nanometers	100 nm	Locus, length of a typical gene
10 ^-6	1 micron	1 µm	Cell nucleus, Plasmodium falciparum
10 ^-5	10 microns	10 µm	Typical primate cell
10 ^-4	100 microns (micrometer)	100 µm	Patch of melanin, width of hair, human egg
10 ^-3	1 millimeter	1 mm	The height of a cusp on a Y-5 molar
10 ^-2	1 centimeter	1 cm	Human ear bones,Anopheles mosquito
10 ^-1	10 centimeters	10 cm	Length of a human's opposable thumb
10 ^0	1 meter	1 m	Space that an individual primate occupies
10 ^1	10 meters	10 m	Typical sleeping area of a primate social group
10 ^2	hectare/ 2.5 acres, football field	100 m	Typical core area of a primate social group
10 ^3	10 hectares, 1 kilometer	1 km	Typical territory of a non-human primate social group
10 ^4	100 hectares	10 km	Typical home range of a non-human primate social group
10 ^5	100 kilometers	100 km
10 ^6	1,000 kilometers, continent	1000 km	Typical range of a non-human primate species; range for most of human evolution
10 ^7	10,000 kilometers, the surface of the planet Earth	100000 km	The range of all biological evolution
10 ^12	1 billion kilometers, 1 terameter	1 Tm	The Earth's orbit in the solar system, includes meteors and solar radiation

Notice that most of the larger ranges are relevant for hominid evolution and primate behavior, the medium sizes are used in osteology and to compare human and hominid variation. The smaller sizes can describe human variation and genetics. Refer back to this chart as we cover those relevant sections.

Exercise \(\PageIndex{1}\)

Use this chart and watch the movie POWERS OF TEN

“Recognize that the very molecules that make up your body, the atoms that construct the molecules, are traceable to the crucibles that were once the centers of high mass stars that exploded their chemically rich guts into the galaxy, enriching pristine gas clouds with the chemistry of life. So that we are all connected to each other biologically, to the earth chemically and to the rest of the universe atomically. That's kinda cool! That makes me smile and I actually feel quite large at the end of that. It's not that we are better than the universe, we are part of the universe. We are in the universe and the universe is in us.”
-Neil deGrasse Tyson

Note

More on scale and measurements: human scale

Imagination Question

When you look in the mirror do you see yourself as a trillion cells, or a trillion, trillion atoms which came from stardust, or a collection of selfish genes, or an individual?