However, one particularity of the human species is that pair bonds are often formed without necessarily having the intention of reproduction.
In modern times, emphasis on the institution of marriage, generally described as a male-female bond, has obscured pair bonds formed by same-sex and transsexual couples, and that many heterosexual couples also bond for life without offspring, or that often pairs that do have offspring separate.
The percentage of 12 C to the remaining 14C shows the time period passed since cessation of life.
Dating technique which makes use of the fact that atmospheric carbon dioxide includes a consistent percentage of radioactive 14C, created by cosmic radiation.Another method of determining absolute age is by looking at varves.VARVES ARE LAYERS OF LIGHT AND DARK SEDIMENT THAT SHOW YEARLY CYCLES. Each spring or summer when the glacier was melting the glacier deposits a ton of sediment it was carrying into strems of water that are melting off of it.RADIOACTIVE ISOTOPES ARE UNSTABLE VERSIONS OF NORMAL ELEMENTS.BECAUSE THEY ARE UNSTABLE THEY GIVE OFF RADIATION TO TRY TO BECOME NORMAL.Living creatures ingest this isotope in an identical percentage.