The mysterious death of Francesco I de' Medici and Bianca Cappello: an arsenic murder?

Dear Professor Sweeney, we had already observed what You say.
It is very difficult to find a document in which Mons.Baldovinetti
states the hours of death in digital form ( 04:00).
Mons.Baldovinetti was probably used to calculate hours according
to the Canonic system wich means twelve hours beginning at
dawn and ending at sunset, and the hours where numbered as
first hour, second hour and so on.
In the description of Mons.Baldovinetti there are 3 main points :
- 4° and 5° hora di notte ( 19 october)
- Martedì mattina (20 october)
- Intervallo di circa 12 hore ( gap of about 12 hours)

Now if you have a look in the enclosure you can realise the
correspondence of the hours; you must take into consideration the
division between daytime (D) and nighttime ( N).

In a separate mail, we are going to send You the complete
explanation in Excel.

Competing interests:
None declared

I’ve read with interest the article of Mari et al. It deals with the
cause of death
of Francesco I de’ Medici and Bianca Cappello, the grand-ducal couple of
Florence died in 1587.
In their very intriguing paper the Authors affirm that “acute poisoning
with
arsenic was the cause of death of Francesco I de’ Medici and Bianca
Cappello,
in contrast to previous theories that attributed their deaths to malaria”.

Indeed, they accurately report the historical fonts that led them to
re-advance
the hypothesis of arsenic poisoning and extensively describe the
methodologies and calculations applied to obtain the arsenic
concentrations
in soft biological tissues (collected from the remains of the broken
terracotta
jars containing, according to historical data, the viscera of Francesco I
de’
Medici and his wife), and in a fragment of femur and in a beard hair of
Francesco I (collected from the grave of the Grand Duke).

By contrast, the Authors very shortly describe the DNA profiling of
the ancient
biological materials analysed. They briefly say that the DNA profiling of
two of
the samples collected within the terracotta jars has “extremely high
degree of
similarity” with the DNA of the small skin fragment found attached to the
beard hair of Francesco I and the DNA profiling of a third sample
“revealed
only its female origin”.

DNA profiling represents an extremely important and fundamental
element in
order to assign the ancient human remains the correct identity and to
answer
the question who were the victims of the hypothesised arsenic murder (the
starting point to develop all the plot!).
Surprisingly, in their article the Authors do not report the methodologies

applied to obtain DNA profiling (i.e. by evaluating microsatellite loci or

mitochondrial DNA regions) and the kind of analysis used to calculate the
degree of similarity.

Moreover, the Authors do not describe conditions (i.e. physically
isolated
work area) and methods applied to perform DNA extraction from ancient
biological materials (i.e soft tissue and bone) and to test the quality
(i.e. PCR
products size) and quantity (i.e. by real time PCR) of the ancient DNA
recovered. They simply say that DNA was extracted from a “small” skin
fragment attached to the beard hair of Francesco I. Why DNA extraction was

not performed from the fragment of femur? This could have allowed for the
possibility to repeat the results by using DNA deriving from a distinct
sample,
a fragment of bone whose surface can be also treated to reduce the
presence
of contaminants (i.e. human DNA, bacterial DNA, etc). Indeed, the results
were not duplicated with different DNA preparations nor validated with
independent replication in different laboratories.

Overall, the Authors do not provide any information, nor cite any
references,
about methods and criteria adopted for ensure and validate the
authenticity
of the results obtained from ancient DNA analyses. Considering that
obtaining authentic DNA sequences from ancient human remains presents
extreme technical difficulties due to the small amounts of DNA, quite
often
degraded, along with the exceptional risk of contamination (1), how can
they
exclude to have obtained results from DNA contaminants?

As principal investigator of the research unit devoted to molecular
paleopathology investigations within the project “Paleogenetics and
molecular
paleopathology of the Medici family: infectious diseases and tumours in
the
XVI-XVIII centuries”, founded by the Italian Ministry of University and
Research (2), I am aware that ancient DNA studies represent a powerful
tool
that can be used to obtain insights into the past (3) and that these
studies are
quite appealing for medical readers. However, a number of problems exist
in
this field that are not often properly taken into account and a rigorous
scientific approach should be used in order to obtain reliable results
(4).

Finally, I believe that questions exist as to how reliable the
conclusions of
Mari’s paper are. As the Authors appropriately say “it is highly probable
that
these soft tissues were among those extracted from the body of Francesco
I”
but this is not enough to rewrite the historical reconstruction of the
death of
Francesco I de’ Medici and his wife, Bianca Cappello.

References.

1. Cooper A, Poinar HN. Ancient DNA: do it right or not at all. Science
2000; 289:1139

2. Progetti di Ricerca di Interesse Nazionale (PRIN), grant 2005, prot. N°

2005067073_005

3. Ottini L, Lupi R, Falchetti M, Fornaciari G, Mariani-Costantini R,
Angeletti
LR. Molecular paleopathology: a novel perspective for biomedical history.
Med
Secoli 2005; 17(1):181-91.

4. Gilbert MTP, Bandelt H-J, Hofreiter M, Barnes I. Assessing ancient DNA
studies. Trends Ecol Evol. 2005; 20:541-544

Laura Ottini, MD

Chair of History of Medicine

Department of Experimental Medicine,
University of Rome “La Sapienza”,
V.le Regina Elena, 324,
00161 Rome - Italy

Competing interests:
None declared