Karyograms were built by using a chemical to trap cell division in its metaphase stage. The chromosomes were then separated, dyed, and sequenced via digital imaging into a numbered karyogram. Humans carried forty-six chromosomes, divided into twenty-three pairs. The monitor showed twenty-eight pairs.

Definitely not human.

Carlton explained, “We built this karyogram from a white blood cell from one of the capuchin monkeys.”

From the general excitement, Lorna knew there remained another shoe to drop.

Paul spoke up, his voice was full of wonder. “Capuchins normally have a complement of twenty-seven pairs of chromosomes.”

Lorna stared at the karyogram on the screen. “But there’s twenty-eight here.”

“Exactly!” Zoë said.

Lorna turned to the facility’s director. “ Carlton, you said you still wanted to repeat the test. Surely this is a lab error.”

“It’s under way, but I suspect we’ll confirm the original findings here.” He nodded to the computer.

“Why’s that?”

Carlton leaned forward, grabbed the computer mouse, and toggled through another five genetic maps. “This next karyogram is from the conjoined twin of the first monkey. Again twenty-eight chromosomal pairs. Same as the first. The next studies are from the lamb, the jaguar cub, the parrot, and this last is from the Burmese python.”

The python?

Frowning, she glanced across the lab to where an incubator housed the clutch of snake eggs. In his desire to confirm what she was beginning to suspect, Carlton must have opened one of the eggs to get at the developing embryo inside and obtain its DNA sample.

“Pythons typically have thirty-six pairs of chromosomes,” Carlton continued. “A mix of micro- and macro-chromosomes.”

Lorna read off the screen. “There are thirty-seven here.”

“That’s right. One pair more than normal. Like all the rest. That’s why I’m sure we’ll get the same results when we run the genetic studies again. It’s beyond statistical probability that the lab came up with the same error six times in a row.”