Our body consists of trillions of cells in various forms and functions, collaborating to sustain life. Gigantic muscle cells overshadow the tiniest cells, such as platelets and red blood cells, in a manner akin to comparing a mouse to an elephant.
Recently, after extensive data analysis on primary cell types in the body, scientists uncovered a predictable mathematical relationship among these cells. They found a reverse correlation between cell size and quantity, implying that there are more of the smaller cells than the larger ones.
Additionally, irrespective of their size, cells from distinct categories contribute equally to the overall body mass, a finding published on September 18 in the Proceedings of the National Academy of Sciences.
The association between number and size “has various designations,” the researcher noted. Ecologists often refer to it as the Sheldon spectrum, named after marine expert Raymond Sheldon.
Sheldon and his peers identified that by sorting plankton by size logarithmically, each size category holds equal organism mass. With an increase in size, the number of organisms within a category diminishes, but the mass remains constant.
In 2021, Hatton and his team demonstrated that this pattern is consistent when evaluating the biomass of marine creatures logarithmically, encompassing “from microbes to gigantic whales,” not solely plankton.
A similar pattern can also be observed in the distribution of words in languages, termed Zipf’s law, coined after linguist George Zipf. For instance, in literary analysis, common short words (e.g., “and” or “is”) prevail, while many longer, less frequent words (e.g., “clarinet” or “legislation”) form the remainder. Unearthing this pattern in human cells required immense data compilation.
Jeffery Shander, an independent investigator, initiated this data collection over ten years ago. A significant portion of his data originated from the International Commission on Radiological Protection, responsible for numerous cadaver autopsies to formulate a standard human model.
However, Hatton highlighted that “the ICRP’s emphasis was on the male form.” The team aimed to deduce data relevant to an average female and child.
This goal, combined with the ICRP’s focus on organs over cells, necessitated diving into extensive research papers. Cumulatively, they sourced information from over 1,500 references, affirming that the reverse size-number trend exists in cells across typical males, females, and children.
The team approximates that an adult man contains about 36 trillion cells, an adult woman around 28 trillion, and a 10-year-old child approximately 17 trillion. These numbers resonate with previous research conclusions, especially given the dominant presence of petite blood cells.
Grasping the exact cell count of each type is vital. The researchers discovered, for example, that lymphocyte numbers had been significantly undervalued — potentially reaching up to 2 trillion instead of the believed 500 billion.
“Lymphocytes play a pivotal role in disease defense,” Hatton remarks, emphasizing their significance in conditions like leukemia and HIV. Furthermore, the cell count is a product of cell division, which, when malfunctioning, can cause cancer.
