What is the meaning of 及ぼし合う in 人間や生物の周囲にあって，意識や行動の面でそれらと何らかの相互作用を及ぼし合うもの?


I was reading the definition of 環境:

> 取り囲んでいる周りの世界。人間や生物の周囲にあって，意識や行動の面でそれらと何らかの相互作用を及ぼし合うもの。

I understand the first sentence it as: "world that is a surrounding-area" or
like "the place around us".

I have, however, problems with understanding what the meaning of 及ぼし合う is:

> 人間や生物の周囲にあって，意識や行動の面でそれらと何らかの相互作用を **及ぼし合う** もの。

I know 及ぼす means "to exert (influence)", but with 合う, I know that the action
is done with someone. On Yahoo, I found a definition of it 互いに影響しあう. With
whom/what is this 及ぼし合う done with?




The core meaning of this type of `masu-stem + 合う` is "mutually". It's
typically translated as "each other" or "together" (4th definition
[here](https://jisho.org/word/%E5%90%88%E3%81%86)) when the targets are
humans, but the targets don't have to be living things. For example, Newton's
law of universal gravitation can be explained as すべての物体は引力を及ぼし **あって** いる.

In your sentence, 人間や生物 and 環境 are the two things that exert influences
mutually; humans and animals influence the surrounding environment, and vice
versa.

  * [Usage of 合える with verb stems](https://japanese.stackexchange.com/q/28012/5010)




The core meaning of this type of `masu-stem + 合う` is "mutually". It's
typically translated as "each other" or "together" (4th definition
[here](https://jisho.org/word/%E5%90%88%E3%81%86)) when the targets are
humans, but the targets don't have to be living things. For example, Newton's
law of universal gravitation can be explained as すべての物体は引力を及ぼし **あって** いる.

In your sentence, 人間や生物 and 環境 are the two things that exert influences
mutually; humans and animals influence the surrounding environment, and vice
versa.

  * [Usage of 合える with verb stems](https://japanese.stackexchange.com/q/28012/5010)

