Royal jelly, a thick, milky substance secreted by young nurse honeybees to feed a bee colonyâs larvae, most notably the queen larvae, is a rich source of nutrients, as well as acetycholine, a neurotransmitter that plays a critical role in cognitive function.
The origin of the eukaryotic cell is a milestone in the evolution of life, since eukaryotes include all complex cells and almost all multicellular organisms. The timing of this series of events is hard to determine; Knoll (2006) suggests they developed approximately 1.6â2.1 billion years ago.
The oldest rocks with evidence of fossil cells date to 3.5 billion years. The oldest rocks with cells large and complex enough to be eukaryotic date to 1.0 billion years. For 2.5 billion years only prokaryotic cells existed on earth. The best hypothesis for the origin of eukaryotic cells was proposed by Lynn Margulis in the early 1970s.