Between 6 and 7 million years ago, , the lineage that includes modern and closely related species from the lineage that led to . Hominins evolved thumbs that could touch other fingertips, enabling them to grasp objects and use tools. The skull, neck, spinal column, hip bones, and leg bones of early hominin species in ways that enabled later species to walk . As their brains increased in size, they developed complex social groups and became culturally advanced. They became excellent hunters and gatherers, controlled , built shelters, and buried their dead. Please help me, thank you :-)

the answer will be a) proteins i believe

the correct answer is:

a population changes in response to a change in the environment.

the nitrogen cycle provides nitrogen to the ecosystem from the atmosphere, ground and oceans. nitrogen is an important component of complex molecules such as amino acids and nucleotides, which lead to the creation of proteins and dna, the building blocks of all life. plants absorb nitrogen in the form of ammonium, nitrate ion and, on rare occasions, as amino acids. animals receive nitrogen necessary for biological processes from feeding on living or dead organic matter.