# Function: populationDensity()

[**lifecycle-kit**](https://jonbogaty.com/lifecycle-kit/api/readme/index.md)

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[lifecycle-kit](https://jonbogaty.com/lifecycle-kit/api/readme/index.md) / [bio-laws](https://jonbogaty.com/lifecycle-kit/api/bio-laws/readme/index.md) / populationDensity


# Function: populationDensity() {#function-populationdensity}


> **populationDensity**(`massKg`): `number`

Defined in: [bio-laws/lifeHistory.ts:107](https://github.com/jbcom/lifecycle-kit/blob/074e4e7b8038d3e2de9eb44c4b5b5aee0ef02b48/src/bio-laws/lifeHistory.ts#L107)

Population density from body mass.

Source: Damuth, J. (1981). "Population density and body size in mammals."
Nature, 290(5808), 699-700.

  log10(D) = 4.23 - 0.75 × log10(M)

Large animals are rare because each one needs more resources. This is what
makes a big creature's world feel empty and a small one's crowded, without
anyone tuning a spawn rate.


## Parameters {#parameters}



### massKg {#masskg}


`number`


## Returns {#returns}


`number`