You have an organ that has evolved beyond those of other humans, granting you certain benefits.

Benefit: When you take this feat, select one of the organs from the following list:

Adrenal Gland: You have an expanded adrenal gland, which increases the flow of adrenaline to your body during stressful situations. Whenever you begin combat, you gain the benefits of the Boost chemical. However, you do not suffer the ill effects of boost, nor any of its debilitating effects.

Heart: Your heart is expanded and can handle more stress, giving you increased endurance. Your Constitution modifier is considered to be doubled for the purposes of any endurance-related tasks.

Lungs: Your evolved lungs capture larger amounts of usable oxygen, doubling the amount of time you are able to hold your breath. Additionally, you gain a +4 bonus to all Fortitude saves against airborne toxins and gases.

Optic Nerve: Your optic nerve is more sensitive to light, granting you a +1 bonus on all Spot and Search checks. Additionally, you gain the benefits of Low-Light Vision (Ex).

Stomach: You are immune to all forms of ingested poison, as your advanced stomach can filter out toxins with almost no negative effects. Additionally, you may go for twice as long as normal without food due to the stomach's ability to more efficiently process nutrients.

Special: This feat can be taken multiple times. Each time it is taken, you must select a different organ from the list above.