Rewriting the history: discovering the human footsteps using a multidisciplinary approach

21 December 2022

The research that is being carried out by the Institute of Agricultural Biology and Biotechnology (IBBA) of CNR includes different lines and, among the animal genetics, we can highlight both the genetic improvement production-oriented and the conservation of biodiversity of Italian local livestock breeds. Many small ruminant breeds have undergone centuries of human-mediated selection. This “improvement” of domestic breeds resulted in a slow replacement of the traditional breeds that in the last century has led to high extinction rates among native breeds, and many indigenous breeds survive only in small feral herds. Starting from the assumption that local breeds are a cultural heritage as well an irreplaceable genetic resource, can we also give them a historical value likewise an archaeological finding or an ancient code waiting to be deciphered?

It is known that the genome contains the information necessary to live and that the evolutive mechanisms are the individual’s adaptative response to the environmental variables. But the genome also retains the signs of demographic events that involved the whole population during its formation. This implies that by analysing the goat breed genome it is possible, for example, to determine with good accuracy if this population has undergone a strong demographic reduction/expansion (i.e. variation in the number of individuals of this population). Additionally, we can know if the population analysed is “purebred” or if it has a certain degree of introgression (i.e. the introduction of allelic variants) from other geographically close or distant breeds. Also, it is possible to date these demographic changes and migration events by using specific statistical methods and bioinformatic tools.

If we can infer human history through archaeological remains and ancient written sources, as well as the more recent application of ancient DNA (aDNA), why not use the genome of organisms that, through their close association with humans, shared a common past involving colonisations, raids and diasporas? For the past year, the Institute of Agricultural Biology and Biotechnology began to analyse the caprine genome of some target breeds that suggested a probable Scandinavian origin.

This idea was born both from a closer inspection of previous published results and from a consideration: small ruminants and especially goats have been transported over land, riverine and maritime routes since their domestication, a history stretching back over 10,000 years. The introduction of agriculture and later metallurgy created and developed a wide trading network that humans used to deliver different commodities: textiles, pottery products, jewels and metal manufacts, slaves, and also domesticated species (plant and animals). Thus, the hypothesis that ancient breeds could have kept some trace of these past events that now can be revealed and dated is reasonable.

For tracing back human history we often look for treasures hidden underground. But what if instead we could assume new routes or settlements that are still not documented and would be based on / suggested by genetic data? Could we consider local breeds as surrogates of the most primitive ones and a “living ancient source”?

The response lies in the progress of this fascinating investigation that has already produced results by using different molecular approaches that offer several advantages since they allow us to study these breeds more deeply. We used three different markers: i) the mitochondrial control region (a classical marker widely used for reconstructing the populations / breeds origin), ii) SNPs (single nucleotide polymorphism, i.e. a genetic variation due to one nucleotide) that at the moment are the most common genetic markers, and iii) a subset of whole genome sequencies (a much more expensive technique but definitely a fine-grained tool). Taken together, these preliminary results suggested weak but still detectable past contacts (gene flow due to the crossbreeding) between some Italian and Irish goat breeds with Scandinavian ones.

Interestingly, previous studies showed a clear association between the ancestral genetic components of the mouse (Mus musculus) and some well documented human migration events like the Viking diaspora. The mouse and other so called “bioproxies” are potentially a great information resource. Moreover, by means of a multidisciplinary approach we can look for analogies and to combine hypothesis and results. For example, comparative studies of human genetics, paleobotanics, chemical and isotopic analyses of the wool / leather (fragments of cloth) found in ancient graves and the metal used for making weapons /objects are just a few tools that allow us to do that. We can also apply the linguistics, especially the onomastic (i.e. the study of names, surnames and place names from the dialect and ancient languages) for getting more evidence on an old commercial and cultural exchange between the tribes that inhabited the areas around the Italian Alps, Celtics and the Norse.

Taking into account these analogies with a multidisciplinary perspective it offers the possibility to add missing pieces to the grand mosaic of human history. Moreover, it could create interesting interdepartmental collaborations within the CNR.

Also, to demonstrate that the ovine and caprine Italian breeds are potentially historic resources could help in rescuing them from oblivion and in preserving them from extinction. Looking at these breeds is looking at ourselves; their origin a mirror revealing our own past.

Author: Arianna Manunza


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