What bone is not present in all five fingers

Phalanges (Most distal) – The bones of the fingers. Each finger has three phalanges, except for the thumb, which has two. The phalanges are the bones of the fingers. The thumb has a proximal and distal phalanx, while the rest of the digits have proximal, middle and distal phalanges. so the thumb dont have the middle phalanges

not necessarily. higher fitness requires the organism to be reproductive successful. for example, an organism at age 10 with 15 offspring is much more fit than an organism at age 15 with only 5 offspring.