, ▁once ▁there ▁was ▁free ▁o xygen ▁in ▁Earth ' s ▁atmosphere , ▁the ▁ability ▁to ▁process ▁o xygen ▁led ▁to ▁w ides p read ▁radiation ▁of ▁life , ▁and ▁is ▁one ▁of ▁the ▁most ▁fundamental ▁stages ▁in ▁the ▁evolution ▁of ▁Earth ' s ▁life forms . ▁ ▁In sp ired ▁by ▁M . ▁ac et iv or ans , ▁a ▁team ▁of ▁P enn ▁State ▁research ers ▁led ▁by ▁James ▁G . ▁Fer ry ▁and ▁Christopher ▁House ▁proposed ▁a ▁new ▁" ther mod ynam ical ▁theory ▁of ▁evolution " ▁in ▁ 2 0 0 6 . ▁ ▁It ▁was ▁observed ▁that ▁M . ▁ac et iv or ans ▁converts ▁carbon ▁mon ox ide ▁into ▁ac et ate , ▁the ▁scient ists ▁hypoth es ized ▁that ▁early ▁" proto - cell s " ▁attached ▁to ▁min eral ▁could ▁have ▁similarly ▁used ▁primitive ▁en zym es ▁to ▁generate ▁energy ▁while ▁ex cre ting ▁ac et ate . ▁ ▁The ▁theory ▁thus ▁sought ▁to ▁un ify ▁the ▁" h eter ot roph ic " ▁theory ▁of ▁early ▁evolution , ▁where ▁the ▁prim ord ial ▁soup ▁of ▁simple ▁mole cules ▁arose ▁from ▁non - bi ological ▁processes , ▁and ▁the ▁" chem o aut ot roph ic " ▁theory , ▁where ▁the ▁earliest ▁life forms ▁created ▁most ▁simple ▁mole cules . ▁ ▁The ▁authors ▁observed ▁that ▁though ▁the ▁" deb ate ▁between ▁the ▁heter ot roph ic ▁and ▁chem ot roph ic ▁theories ▁revol ved ▁around ▁carbon ▁fix ation ", ▁in ▁actual ity ▁" th ese