Toberhead McCool Research Status

Date: [unknown] [unknown]
Location: [unknown]
Surnames/tags: McCool McCoole

As of May 2023, there isn't a single living person in the world who is a "solidly supported" Toberhead McCool descendant. Current research will try to change that.

Contents 1 Toberhead McCool Definition 1.1 "Solidly Supported" Toberhead Descendant Definition 2 Human DNA Chromosome Basics 3 Y-DNA Testing 3.1 Y-STR Testing 3.2 Y-SNP Testing 4 Line 1 4.1 Haplogroup R-FT303841

Toberhead McCool Definition

A Toberhead McCool is defined as someone who descends from John McCoole (abt.1645-1719). The line is labeled "Toberhead" because John established the Hillmount Farm in the late 1600s in Toberhead Townland, County Londonderry, Ireland (now Northern Ireland). Hillmount remained in the McCoole family for many generations. Well-preserved ruins of the farm buildings still stand.

Hillmount was always passed to the first-born son. Many descendants who didn't inherit emigrated to America. Some descendants retained the McCoole spelling, while others would use McCool.

"Solidly Supported" Toberhead Descendant Definition

Nothing in genealogy is ever fully "proven." There's always an alternative explanation, no matter how far-fetched. The best researchers can do is to document a strong paper trail and try to support it with DNA testing.

Autosomal DNA (atDNA) tests like AncestryDNA can support that people are likely related within several generations, but can't determine how they're related. Matching Y-DNA tests (especially Big Y-700 tests), however, absolutely confirm that the tested men share a paternal-line ancestor. If two McCool men match on a Y-DNA test, then they share a McCool ancestor. We still require a strong paper trail (and ideally multiple matches) to try to determine the most likely identity of the common ancestor.

Our current problem, as of May 2023, is that we have two different group of Y-DNA tested men who believe that they descend from John McCoole. One or both of these sets of men do not.

Human DNA Chromosome Basics

Under construction

Almost every human cell includes 23 chromosome pairs; one of each pair is inherited from each parent. We label those pairs as 1 to 23. The first 22 pairs are called autosomes while the 23rd pair is the sex (gender) chromosome.

Males have an X Chromosome (inherited from their mother) and a Y Chromosome (inherited from their father) as their 23rd pair of chromosomes. Women inherit one X chromosome from their father and a second X chromosome from their mother.

Y-DNA Testing

Only males carry a Y chromosome. The Y chromosome is passed down in its entirety from father to son to grandson (like surnames are in most modern western societies). Mutations on the Y chromosome are relatively rare, allowing researchers to use those occasional mutations to estimate how closely two tested might be related.

There are two types of areas on the Y chromosome that are used for Y-DNA testing: STRs and SNPs.

Y-STR Testing

To be added

Y-SNP Testing

Much of the Y chromosome is very stable.

Line 1

Haplogroup R-FT303841

This is the newest named haplogroup in the family. The SNP position is 8,389,232, with a mutation from G to C. Only two tested men at FamilyTreeDNA currently carry this mutation; both are McCools.

The most recent common McCool ancestor of anyone with this mutation was born about 1739 CE (Common Era, formerly AD). The actual birth year could range from 1529 to 1878 CE. More Big Y tests from descendants would improve the reliability of this figure.