Human muscular tissue, which is often compared to that of pigs, qualifies scientifically as red meat due to the presence of myoglobin, according to io9. Myoglobin is a protein that stores oxygen for sustained muscle activity and gives raw meat its red color.
Slow-twitch muscles use myoglobin to gather oxygen for extended periods of activity, as opposed to fast-twitch muscles, which use glycogen for their energy source, explains Exploratorium. Beef, which has high concentrations of myoglobin, is a distinctly red meat, visible in the raw flesh. Chicken, in contrast, has clearly distinguishable white and dark muscles. Pork, while often hailed as "the other white meat," is actually a red meat that contains myoglobin, but it is not as densely packed with the protein as beef, so it appears more white. Human flesh, often known as "long pig," has similar levels of myoglobin.